Retry idempotent operations automatically

Nobody has claimed this yet.

There are various situations where an operation can fail:

- A read operation may fail when a client attempts to access the revision in a replica with replication delay. In this case, the failure can be easily recovered by retrying after a small delay.
- A replica may go offline due to some reason (e.g. machine dead, process killed, ...) and thus an operation may fail unexpectedly. If the operation is a read operation, we can just retry against another replica.

Currently, the client library exposes the situations mentioned above to our users as they are, forcing them to implement the recovery and retry logic by themselves. `centraldogma-client` should take care of them so that they don't have to.

We may also want to insert an artificial delay into `watchRepository()` or `watchFile()` operation so that the successive read operations have less chance of getting `RevisionNotFoundException`, as well as implementing the forementioned automatic retry mechanism.

Start by tracing the centraldogma-client paths for watchRepository(), watchFile(), and read operations, including where RevisionNotFoundException is exposed. Determine which idempotent failures and replica responses are in scope, then add focused tests that define retry behavior and completion criteria.

Written by the indexing model from the issue text.