Asynchronously rewrite git history

Problem

Related to https://gitlab.com/gitlab-org/gitlab/-/issues/450701+.

In 17.2 we implemented a new feature Remove blobs that allows to reduce the repository size by removing blobs or redacting text in repositories.

However, this feature doesn't work with large repositories. Here's why:

1. History rewriting is computationally intensive, especially for large repos.
2. The rewriting process can take several minutes to complete.
3. Our application has a 60-second timeout for client requests.

As a result, the process often fails for large repositories because it takes too long and exceeds the timeout limit. For more details, see issue GRPC::DeadlineExceeded exception when removing ... (#475250 - closed).

Proposal

Use an asynchronous processing instead of synchronous.

This approach will:

1. Solve a timeout problem, because Sidekiq doesn't have a 60 seconds limitation.
2. Improve the customer experience. The customer doesn't have to keep the page open during the whole rewrite history process.

To implement that we can:

1. Add support for asynchronous processing on backend side
2. Update UX to indicate that Remove blobs and Redact text processes won't be completed immediately and provide notifications to the user about current status of the processing.
3. Update frontend to support new changes

We can also consider using GraphQL subscriptions to receive real-time updates from the rewrite history process. But it will require extra work on backend and frontend to implement and can be done as a follow-up.