Minimal octez-rpc-server that redirects to the node

This is the second attempt to merge this code. The first attempt was reverted by !9548 (merged), in a hurry, to fix the CI. Indeed, it appears that the slight memory consumption added (expected) by this MR was make the CI flaky. In particular, the test p2p-swap-disable was barely passing.

Please refer to !8946 (merged) for all the MR details

What fixed the CI?:

• the greedy tag to help the CI not to be out of resources
• lower down the memory consumption of some tests (!9715 (merged) !9656 (merged) !9587 (merged))
• remove tests flakiness (!9663 (merged))
• Slow down the rpc_process watchdog (The Unix.waitpid was catching the kill signals faster than the Lwt_exit overlay. Thus, assuming that the rpc_process needed to be restarted when down and when Lwt_exit was sleeping was not valid. This was resulting in unexpected rpc_process restarts, causing tests/CI hangs and issues with ports attribution.)

Manually testing the MR

Green CI. See !8946 (merged)

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• [n/a] Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• [n/a] 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