Rename instructions with immediate values + add ShiftAmount

[Robbepop]

This PR looks bigs and scary but it does not introduce new instructions or change their encoding or semantics.
The new ShiftAmount abstractions improves type safety of Instruction.

• Renames commutative instructions to better reflect if rhs or lhs is an immediate value.
• Rename shift and rotate instructions with immediate shift amount to x_by, e.g. shl_by.
• Remove unnecessary _lhs affix from shift and rotate instructions that have an immediate value.
• Add new wasmi_ir::ShiftAmount abstraction.

[codecov]

Codecov Report

Attention: Patch coverage is 85.06151% with 85 lines in your changes missing coverage. Please review.

Project coverage is 81.34%. Comparing base (d22362a) to head (a2f3f4b).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/wasmi/src/engine/executor/instrs.rs	41.77%	46 Missing ⚠️
crates/wasmi/src/engine/translator/visit.rs	0.00%	38 Missing ⚠️
crates/wasmi/src/engine/executor/instrs/binary.rs	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1221      +/-   ##
==========================================
+ Coverage   81.30%   81.34%   +0.03%     
==========================================
  Files         303      303              
  Lines       25025    25032       +7     
==========================================
+ Hits        20347    20362      +15     
+ Misses       4678     4670       -8     

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