Create snippet repository move in bulks scheduler service and worker

What does this MR do?

This MR creates the snippets' ScheduleBulkRepositoryShardMovesService service and ScheduleBulkSnippetUpdateRepositoryStorageWorker worker. This worker and service will allows us to schedule snippet repository storage moves in bulk. These operations will be triggered by some API endpoints developed in !49228 (merged).

We already have the Projects::ScheduleBulkRepositoryShardMovesService service, and the good news is that we can reuse most of the logic, so we extracted it into a concern and reused it. We also have Projects::ScheduleBulkSnippetUpdateRepositoryStorageWorker worker but the logic inside it is so simple that it wasn't a good candidate to refactor anything.

Does this MR meet the acceptance criteria?

Conformity

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

Related to #218991 (closed)