Tezlink/Node: forward operations in RPC mode

What

Stacked on !17697 (merged).

Closes L2-88

Make the L2 node in RPC mode able to forward Tezlink operations to its upstream L2 node.

Like the previous MR (!17697 (merged)) this MR defines the Tezlink version of the container but does not make any use of it; even in Tezlink mode the L2 node still uses only Etherlink tx containers.

Why

Since the sequencer does not support all the Tezlink RPCs, the minimal setup for Tezlink consists in a L2 node in sequencer mode + a L2 node in RPC mode on the same data dir. The RPC node is the one who receives new Tezlink operations first and needs to be able to forward them to the sequencer.

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