Minor refactor of storage provider stringer (#4228)

<!-- PR description-->

One of the setup PRs before introducing local storage support for corso.

Changes
1. Export `storage.storageProvider` and rename it to `storage.Provider`. Without the rename, linter errors out with `exported: type name will be used as storage.StorageProvider by other packages, and that stutters; consider calling this Provider`
2. Rerun stringer - `stringer -type=Provider -linecomment`
3. Introduce a new Provider - `FS` for filesystem. This is in line with kopia naming for local/network attached storage.
4. Fix hardcoded string values for storage providers in test code.
---

#### Does this PR need a docs update or release note?

- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No

#### Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [x] 🧹 Tech Debt/Cleanup

#### Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* #<issue>

#### Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

src/cli/backup/helpers_test.go

@@ -144,8 +144,8 @@ func prepM365Test(
 	require.NoError(t, err, clues.ToCore(err))
 
 	force := map[string]string{
-		tconfig.TestCfgAccountProvider: "M365",
-		tconfig.TestCfgStorageProvider: "S3",
+		tconfig.TestCfgAccountProvider: account.ProviderM365.String(),
+		tconfig.TestCfgStorageProvider: storage.ProviderS3.String(),
 		tconfig.TestCfgPrefix:          cfg.Prefix,
 	}
 

src/cli/repo/s3_e2e_test.go

@@ -18,6 +18,7 @@ import (
 	"github.com/alcionai/corso/src/pkg/control"
 	ctrlRepo "github.com/alcionai/corso/src/pkg/control/repository"
 	"github.com/alcionai/corso/src/pkg/repository"
+	"github.com/alcionai/corso/src/pkg/storage"
 	storeTD "github.com/alcionai/corso/src/pkg/storage/testdata"
 )
 
@@ -185,8 +186,8 @@ func (suite *S3E2ESuite) TestConnectS3Cmd() {
 			require.NoError(t, err, clues.ToCore(err))
 
 			force := map[string]string{
-				tconfig.TestCfgAccountProvider: "M365",
-				tconfig.TestCfgStorageProvider: "S3",
+				tconfig.TestCfgAccountProvider: account.ProviderM365.String(),
+				tconfig.TestCfgStorageProvider: storage.ProviderS3.String(),
 				tconfig.TestCfgPrefix:          cfg.Prefix,
 			}
 			vpr, configFP := tconfig.MakeTempTestConfigClone(t, force)

src/cli/restore/exchange_e2e_test.go

@@ -70,8 +70,8 @@ func (suite *RestoreExchangeE2ESuite) SetupSuite() {
 	require.NoError(t, err, clues.ToCore(err))
 
 	force := map[string]string{
-		tconfig.TestCfgAccountProvider: "M365",
-		tconfig.TestCfgStorageProvider: "S3",
+		tconfig.TestCfgAccountProvider: account.ProviderM365.String(),
+		tconfig.TestCfgStorageProvider: storage.ProviderS3.String(),
 		tconfig.TestCfgPrefix:          cfg.Prefix,
 	}
 	suite.vpr, suite.cfgFP = tconfig.MakeTempTestConfigClone(t, force)

src/pkg/storage/providertype_string.go

@@ -0,0 +1,25 @@
+// Code generated by "stringer -type=ProviderType -linecomment"; DO NOT EDIT.
+
+package storage
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[ProviderUnknown-0]
+	_ = x[ProviderS3-1]
+	_ = x[ProviderFilesystem-2]
+}
+
+const _ProviderType_name = "Unknown ProviderS3Filesystem"
+
+var _ProviderType_index = [...]uint8{0, 16, 18, 28}
+
+func (i ProviderType) String() string {
+	if i < 0 || i >= ProviderType(len(_ProviderType_index)-1) {
+		return "ProviderType(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _ProviderType_name[_ProviderType_index[i]:_ProviderType_index[i+1]]
+}

src/pkg/storage/storage.go

@@ -8,12 +8,13 @@ import (
 	"github.com/alcionai/corso/src/internal/common"
 )
 
-type storageProvider int
+type ProviderType int
 
-//go:generate stringer -type=storageProvider -linecomment
+//go:generate stringer -type=ProviderType -linecomment
 const (
-	ProviderUnknown storageProvider = 0 // Unknown Provider
-	ProviderS3      storageProvider = 1 // S3
+	ProviderUnknown    ProviderType = 0 // Unknown Provider
+	ProviderS3         ProviderType = 1 // S3
+	ProviderFilesystem ProviderType = 2 // Filesystem
 )
 
 // storage parsing errors
@@ -24,7 +25,7 @@ var (
 // Storage defines a storage provider, along with any configuration
 // required to set up or communicate with that provider.
 type Storage struct {
-	Provider storageProvider
+	Provider ProviderType
 	Config   map[string]string
 	// TODO: These are AWS S3 specific -> move these out
 	SessionTags     map[string]string
@@ -34,7 +35,7 @@ type Storage struct {
 }
 
 // NewStorage aggregates all the supplied configurations into a single configuration.
-func NewStorage(p storageProvider, cfgs ...common.StringConfigurer) (Storage, error) {
+func NewStorage(p ProviderType, cfgs ...common.StringConfigurer) (Storage, error) {
 	cs, err := common.UnionStringConfigs(cfgs...)
 
 	return Storage{
@@ -46,7 +47,7 @@ func NewStorage(p storageProvider, cfgs ...common.StringConfigurer) (Storage, er
 // NewStorageUsingRole supports specifying an AWS IAM role the storage provider
 // should assume.
 func NewStorageUsingRole(
-	p storageProvider,
+	p ProviderType,
 	roleARN string,
 	sessionName string,
 	sessionTags map[string]string,

src/pkg/storage/storage_test.go

@@ -28,7 +28,7 @@ func TestStorageSuite(t *testing.T) {
 func (suite *StorageSuite) TestNewStorage() {
 	table := []struct {
 		name     string
-		p        storageProvider
+		p        ProviderType
 		c        testConfig
 		errCheck assert.ErrorAssertionFunc
 	}{

src/pkg/storage/storageprovider_string.go

@@ -1,24 +0,0 @@
-// Code generated by "stringer -type=storageProvider -linecomment"; DO NOT EDIT.
-
-package storage
-
-import "strconv"
-
-func _() {
-	// An "invalid array index" compiler error signifies that the constant values have changed.
-	// Re-run the stringer command to generate them again.
-	var x [1]struct{}
-	_ = x[ProviderUnknown-0]
-	_ = x[ProviderS3-1]
-}
-
-const _storageProvider_name = "Unknown ProviderS3"
-
-var _storageProvider_index = [...]uint8{0, 16, 18}
-
-func (i storageProvider) String() string {
-	if i < 0 || i >= storageProvider(len(_storageProvider_index)-1) {
-		return "storageProvider(" + strconv.FormatInt(int64(i), 10) + ")"
-	}
-	return _storageProvider_name[_storageProvider_index[i]:_storageProvider_index[i+1]]
-}