Sort imports in WikibaseRepo class

Change-Id: Id829080070034240fb3346133b7cdf9c734842b7
Move EntityPermissionChecker to repo, as not used elsewhere

Change-Id: I7c84508dfead8fdd4808b44b5e2481779ec8fe6f
Merge "Sort imports in WikibaseRepo class"
Merge "Move EntityPermissionChecker to repo, as not used elsewhere"