Azure blob storage support (#30995)

This PR implemented object storages(LFS/Packages/Attachments and etc.)
for Azure Blob Storage. It depends on azure official golang SDK and can
support both the azure blob storage cloud service and azurite mock
server.

Replace #25458
Fix #22527 

- [x] CI Tests
- [x] integration test, MSSQL integration tests will now based on
azureblob
  - [x] unit test 
- [x] CLI Migrate Storage
- [x] Documentation for configuration added

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TODO (other PRs):
- [ ] Improve performance of `blob download`.

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Co-authored-by: yp05327 <576951401@qq.com>

modules/storage/storage_test.go

@@ -35,6 +35,7 @@ func testStorageIterator(t *testing.T, typStr Type, cfg *setting.Storage) {
 		"b":           {"b/1.txt", "b/2.txt", "b/3.txt", "b/x 4.txt"},
 		"":            {"a/1.txt", "b/1.txt", "b/2.txt", "b/3.txt", "b/x 4.txt", "ab/1.txt"},
 		"/":           {"a/1.txt", "b/1.txt", "b/2.txt", "b/3.txt", "b/x 4.txt", "ab/1.txt"},
+		".":           {"a/1.txt", "b/1.txt", "b/2.txt", "b/3.txt", "b/x 4.txt", "ab/1.txt"},
 		"a/b/../../a": {"a/1.txt"},
 	}
 	for dir, expected := range expectedList {