codegen: Use idiomatic fuel-vm ops for memcpy and addr_of

[Dentosal]

Description

SIgnificantly reduces bytecode sizes by transforming the following commonly-used operations when the constant value fits into the immediate part of the *i variant of the instruction:

• MOVI(tmp, copy_len); MCP(dst, src, tmp) → MCPI(dst, src, copy_len) (in compile_mem_copy_bytes)
• MOVI(dst, offset); ADD(dst, dst, DATA_SECTION) → ADDI(dst, DATA_SECTION, offset) (in addr_of)

Checklist

• I have linked to any relevant issues. (none that I know of)
• 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). (no changes required)
  • 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. (partially; some values in tests got smaller. we don't seem to be tracking the size and size regressions in tests)
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant. (not 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 #6795 will not alter performance

_{Comparing dento/idiomatic-opcode-optimizations (4fb9bcc) with master (1192b3f)}

Summary

✅ 22 untouched benchmarks