Use python to implement the cleanup directive

[linsword13]

Previously the cleanup directive was implemented using find with the posix-extended support. This makes it not very portable for various platforms. Piggybacking on the work done in #1559, it now uses python to implement the cleanup.

This assumes that python3 is more widely available, for the platforms we aim to support.

[gemini-code-assist]

Code Review

This pull request replaces the platform-dependent find command used in cleanup directives with a cross-platform Python-based cleaner utility script (_ramble_cleaner.py). The feedback highlights a potential runtime failure where the cleaner script is incorrectly guarded by the generate_file_editing_scripts configuration, meaning it won't be written if that config is disabled. Additionally, suggestions were made to simplify the cleaner script by using re.fullmatch and removing an unused is_dir flag in the file deletion loop.

[ramble-pr-bot]

Ramble Performance Test Metrics

Results produced with commit: a3432b1

Test Name	Outcome	Duration (s)	Most Recent Run (s)	Last 5 Avg (s)
test_analyze_large_file	passed	2.9898	2.9922 (013099b)	2.9973
test_large_template_expansion	passed	2.4079	2.1188 (013099b)	2.1363
test_many_experiments	passed	36.1022	32.2892 (013099b)	33.2663
test_many_objects_defaults	passed	20.0070	18.3797 (013099b)	18.4377
test_matrix_filter_perf	passed	1.6943	1.5916 (013099b)	1.6218

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.02%. Comparing base (013099b) to head (a3432b1).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1625   +/-   ##
========================================
  Coverage    93.02%   93.02%           
========================================
  Files          348      349    +1     
  Lines        33858    33862    +4     
========================================
+ Hits         31497    31501    +4     
  Misses        2361     2361           

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