Subroutine calls using the new JAL instruction

[Dentosal]

Description

Waiting for FuelLabs/fuel-vm#925 and a subsequent releases of fuel-vm, fuel-core and possibly fuels-rs as well. That also means compiling code on this branch requires you to do lots of manual insertion of [patch] segments in Cargo.toml files of related projects. It also just comments-out or removes some code that blocks compilation with simple patches, and those changes must be reverted before merging.

This PR contains an initial implementtion of subroutine calls using the in-progress jump-and-link instruction JAL. It doesn't have any tests yet and might be entirely broken, but shows the basic idea regardless.

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.