Rollup node: track outbox messages execution

What

This MR tracks which outboxes become executable and which messages have been executed. It also adds RPCs to the rollup node to fetch this information.

Why

This information is useful for both users and tool developers. It is also required to implement automatic outbox execution.

How

A new storage entry in the rollup node in the form of a hash table of bitsets.

Manually testing the MR

dune exec tezt/tests/main.exe -- -f sc_rollup.ml outbox