Rollup-Node: FUELED_PVM module uses mutable API when using PVMs

What

Closes of RV-184

• Uses the mutable pvm API in FUELED_PVM used by the rollup node.

Why

• Using a mutable API will enable ownership/move semantics to be used in the RISCV implementation of the PVM which will help avoid doing extraneous state copies when the PVM is used in a linear fashion.

How

The FUELED_PVM module will now use the mutable PVM API as follows:

• Where we want mutable api usage, take the immutable state, use conversion functions between mutable and immutable states.
• Then, use the Mut_api functions which will not return a new state, but modify it in place (by returning a unit Lwt.t / <side_effect_data> Lwt.t)
• Convert the mutable state back to immutable.

Manually testing the MR

The mutable API will be used in the FUELED_PVM module which is tested by rollup node tests.

make
# Just the rollup node tests
dune exec ./tezt/tests/main.exe -- --verbose --file tezt/tests/sc_rollup.ml
# Alternatively all tests
make test

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