frontend: (pyast) support classmethods

[Time0o]

This adds classmethod support to Python code generation so that we can now write e.g. the following instead of having to create a wrapper function:

@ctx.parse_program
def constant_replace_wrapper(matched_operation: arith.ConstantOp):
    Rewriter.erase_op(matched_operation)

[codecov]

Codecov Report

❌ Patch coverage is 90.62500% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.15%. Comparing base (a4ee22a) to head (93b0a7c).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
xdsl/frontend/pyast/code_generation.py	90.62%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5595   +/-   ##
=======================================
  Coverage   86.15%   86.15%           
=======================================
  Files         392      393    +1     
  Lines       56271    56333   +62     
  Branches     6485     6496   +11     
=======================================
+ Hits        48478    48535   +57     
- Misses       6261     6264    +3     
- Partials     1532     1534    +2     

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[Time0o]

@superlopuh How critical is code coverage? I suppose the missing else branch could be covered by trying to call something that is neither a function nor classmethod

[superlopuh]

Great! Thank you