Add progress logging to uploader (#4672)

Adds a progress log in the kopia upload that logs every 10000 files that have been uploaded.

This is useful to track progress of large backups.

---

#### 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
- [x] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

#### Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* #4670 

#### Test Plan

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

src/internal/kopia/upload.go

@@ -57,6 +57,7 @@ type corsoProgress struct {
 	toMerge    *mergeDetails
 	mu         sync.RWMutex
 	totalBytes int64
+	totalFiles int64
 	errs       *fault.Bus
 	counter    *count.Bus
 	// expectedIgnoredErrors is a count of error cases caught in the Error wrapper
@@ -91,6 +92,13 @@ func (cp *corsoProgress) FinishedFile(relativePath string, err error) {
 		return
 	}
 
+	atomic.AddInt64(&cp.totalFiles, 1)
+
+	// Log every 1000 items uploaded
+	if cp.totalFiles%1000 == 0 {
+		logger.Ctx(cp.ctx).Infow("finishedfile", "totalFiles", cp.totalFiles, "totalBytes", cp.totalBytes)
+	}
+
 	d := cp.get(relativePath)
 	if d == nil {
 		return