Reduce cmp and cmp+br instructions

[Robbepop]

This reduces i{32,64}.{gt,ge}_{s,u} and f{32,64}.{gt,ge} instructions into respective {lt,le} variants.
Fused cmp+br instructions are also affected by the above change.

To support this, new {lt,le} variants with 16-bit immediate lhs values have been added.

Overall this reduces the total amount of Wasmi instructions by 24 which is quite significant.

Local benchmarks show significant improvements across the board:

[codecov]

Codecov Report

Attention: Patch coverage is 63.82979% with 204 lines in your changes missing coverage. Please review.

Project coverage is 81.44%. Comparing base (5ec8bb8) to head (a594ada).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/wasmi/src/engine/translator/comparator.rs	44.59%	123 Missing ⚠️
crates/wasmi/src/engine/executor/instrs.rs	30.23%	30 Missing ⚠️
crates/wasmi/src/engine/translator/visit.rs	3.44%	28 Missing ⚠️
...rates/wasmi/src/engine/translator/instr_encoder.rs	79.46%	23 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1243      +/-   ##
==========================================
- Coverage   81.77%   81.44%   -0.34%     
==========================================
  Files         304      304              
  Lines       25144    25036     -108     
==========================================
- Hits        20561    20390     -171     
- Misses       4583     4646      +63     

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[dkcumming]

I had a bit of trouble with the executor, as I am less experienced at that part, but it I couldn't see anything that looked wrong. The rest of the code ir, executor, instrs, tests I was more thorough and understood better and all looks good to me!

[Robbepop]

I had a bit of trouble with the executor, as I am less experienced at that part, but it I couldn't see anything that looked wrong. The rest of the code ir, executor, instrs, tests I was more thorough and understood better and all looks good to me!

Thank you for the code review @dkcumming ! 🚀 Really appreciate it.
You probably meant that you had troubles with the translator, not the executor.