Create Groups::UpdateRepositoryStorageService service

What does this MR do?

In this MR we introduce the Groups::UpdateRepositoryStorageService. This service will be used to handle groups repository storage moves. This is very similar to the one used for projects and snippets. We just need to override several methods in order to customize them for groups.

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content

Related to #299057 (closed)