transmute intrinsics

[xunilrj]

Description

This PR implements the __transmute intrinsic. As Rust this intrinsic should be a no-op semantically equal to a pointer cast. Although this PR does not aim that it is 100% no-op yet.

At the moment some trade-offs were taken:

1 - References, pointers etc... are not allowed at the moment;
2 - u16 and u32 actually occupy 64bits. To allow transmute to work in complex aggregates, this PR is accepting them as u64. Doing otherwise would forbid __transmute to be no-op. Specially in complex aggregates;

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.

[codspeed-hq]

CodSpeed Performance Report

Merging #6692 will not alter performance

_{Comparing xunilrj/transmute-intrinsics (c811da9) with master (861ca10)}

Summary

✅ 22 untouched benchmarks