Refactor jump label realization

[Dentosal]

Description

Simplifies jump instruction generation, moving the actual instruction selection to a single location. Removes lots of error-prone duplicate logic around far jump rewriting. This theoretically has a slight size penalty in jump-heavy contracts, but in practice this should be neglible. For instance mira-v1-core isn't affected at all. This PR is makes it easier to implement further optimizations, especially those around the new JAL instruction and u16/u32 integer loading opcodes. In particular, data section packing should be a lot easier after this.

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: just a refactor, existing tests suffice
• 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.

[codspeed-hq]

CodSpeed Performance Report

Merging #7088 will not alter performance

_{Comparing dento/rework-far-jumps (8fd1f4c) with master (aafcdc8)}

Summary

✅ 22 untouched benchmarks