Shell: move validator specific RPCs to dedicated rpc directory

This simple MR, in the context of !9490 and %Non-blocking RPC feature as experimental, aims to move some node specific RPCs (that requires the validation tool chain) to the dedicated RPC directory. Indeed, the handling of Invalid_blocks and liveblocks are handled by the the node thanks to the validation result (triggering the invalid block classification or the set_head (triggering the liveblock computation)). The external RPC process is not capable of dealing with these RPCs.

Manually testing the MR

Green CI

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