[Storage] `DataLakePathClient` APIs are not creating scopes when being called directly

[amnguye]

Currently our DataLakePathClient tests are being tested through calling it's derived clients (e.g. DataLakeFileClient and DataLakeDirectoryClient). And when being called directly you would get a no scope detected error.

This was probably done intentionally not to accidentally create a double scope. However I think the correct way to go about this is to create the scope in the PathClient and pass the resource scope name to the PathClient, instead of starting it in the FileClient and DirectoryClient.