export repoExists error from repository (#1335)

## Description

Intercept the lower-level RepoAlreadyExists error, and field a repository package version of the same error for sdk consumers to identify when initializing corso repos.

## Type of change

- [x] 🌻 Feature

## Issue(s)

* #1136

## Test Plan

- [x] 💪 Manual
- [x] 💚 E2E

src/cli/repo/s3.go

@@ -9,7 +9,6 @@ import (
 	"github.com/alcionai/corso/src/cli/options"
 	. "github.com/alcionai/corso/src/cli/print"
 	"github.com/alcionai/corso/src/cli/utils"
-	"github.com/alcionai/corso/src/internal/kopia"
 	"github.com/alcionai/corso/src/pkg/account"
 	"github.com/alcionai/corso/src/pkg/repository"
 	"github.com/alcionai/corso/src/pkg/storage"
@@ -121,7 +120,7 @@ func initS3Cmd(cmd *cobra.Command, args []string) error {
 
 	r, err := repository.Initialize(ctx, a, s, options.Control())
 	if err != nil {
-		if succeedIfExists && kopia.IsRepoAlreadyExistsError(err) {
+		if succeedIfExists && errors.Is(err, repository.ErrorRepoAlreadyExists) {
 			return nil
 		}
 

src/cli/repo/s3_integration_test.go

@@ -76,6 +76,11 @@ func (suite *S3IntegrationSuite) TestInitS3Cmd() {
 
 			// run the command
 			require.NoError(t, cmd.ExecuteContext(ctx))
+
+			// a second initialization should result in an error
+			err = cmd.ExecuteContext(ctx)
+			assert.Error(t, err)
+			assert.ErrorIs(t, err, repository.ErrorRepoAlreadyExists)
 		})
 	}
 }

src/pkg/repository/repository.go

@@ -2,6 +2,7 @@ package repository
 
 import (
 	"context"
+	"errors"
 	"time"
 
 	"github.com/google/uuid"
@@ -20,6 +21,8 @@ import (
 	"github.com/alcionai/corso/src/pkg/store"
 )
 
+var ErrorRepoAlreadyExists = errors.New("a repository was already initialized with that configuration")
+
 // BackupGetter deals with retrieving metadata about backups from the
 // repository.
 type BackupGetter interface {
@@ -78,6 +81,11 @@ func Initialize(
 ) (Repository, error) {
 	kopiaRef := kopia.NewConn(s)
 	if err := kopiaRef.Initialize(ctx); err != nil {
+		// replace common internal errors so that sdk users can check results with errors.Is()
+		if kopia.IsRepoAlreadyExistsError(err) {
+			return nil, ErrorRepoAlreadyExists
+		}
+
 		return nil, err
 	}
 	// kopiaRef comes with a count of 1 and NewWrapper/NewModelStore bumps it again so safe