Baker/operation_worker: improve RPC failure resilience

What

Fix a behavior where the operation worker shuts down without shutting down the baker.

Add a watchdog to detect inactivity in the monitor_operations RPC stream and refresh it on timeout.

Note for reviewers: The proto_patch script failed to backport most of the changes, so I had to apply many of them manually. Please review carefully.

Why

How

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR