Add /monitor/(validated|applied)_blocks RPC

Context

This MR deprecates the /monitor/valid_blocks RPC and introduces the alternative /monitor/applied_blocks that has a different output format and also includes operations.

It also introduces /monitor/validated_blocks which notifies every newly validated block (formerly prechecked) using the same output format as /monitor/applied_blocks

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