Use Python extension with libwcwidth

[jquast]

This prepares a 0.9.0 release, which only enables use of C11 libwcwidth as optional Python extension. This PR makes no logical changes to the python library behavior except to improve performance ~10-58x by use of the optional build_ext.

This creates a new release process, documented in docs/developing.rst. tox -e check_release calls bin/check-release.py to help ensure all wheels are included.

A lot of care was done to make it safe to release to general public, that it should be possible to install from sdist even if compilation fails or is unavailable and gracefully fallback to pure python. cibuildwheel is used to build binaries, and, because we distribute a "python3-none-any" (any os, any architecture), that, if no build wheel exists, then package installs will use the python-only wheel without any error or warning.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (97b4df6) to head (77fda52).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #248   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           27        27           
  Lines         2008      2040   +32     
  Branches       468       473    +5     
=========================================
+ Hits          2008      2040   +32     

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[codspeed]

Merging this PR will improve performance by ×9.9

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 79 improved benchmarks
✅ 40 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	test_wcswidth_ri_flags_paired	342.7 ms	5.9 ms	×58
⚡	test_width_ri_flags_paired	342.9 ms	5.9 ms	×58
⚡	test_wcstwidth_ri_term_program[ghostty]	344 ms	6 ms	×58
⚡	test_width_ri_term_program[ghostty]	344.2 ms	6 ms	×57
⚡	test_wcswidth_ri_flags_unpaired	85.9 ms	1.5 ms	×57
⚡	test_wcstwidth_ri_term_program[xterm.js]	345.4 ms	6.1 ms	×57
⚡	test_width_ri_flags_unpaired	86 ms	1.5 ms	×57
⚡	test_width_ri_term_program[xterm.js]	345.6 ms	6.1 ms	×57
⚡	test_width_udhr	585.7 ms	13.7 ms	×43
⚡	test_clip_long_cjk_to_end	11,784.4 µs	278.9 µs	×42
⚡	test_clip_cjk_paragraph	11,709.6 µs	278.1 µs	×42
⚡	test_clip_dense_ansi_to_end	12,460 µs	303.1 µs	×41
⚡	test_clip_dense_ansi_to_end_no_propagate	10,114.5 µs	283.3 µs	×36
⚡	test_wcstwidth_emoji_term_program[ghostty]	1,373.6 µs	41.8 µs	×33
⚡	test_wcswidth_decomposed	2,600.1 µs	81.1 µs	×32
⚡	test_width_fastpath_integrity_udhr	739.7 ms	23.8 ms	×31
⚡	test_clip_dense_ansi_no_propagate	2,419.6 µs	86.1 µs	×28
⚡	test_width_udhr_lines	319.5 ms	12.1 ms	×26
⚡	test_wcswidth_composed	1,863.8 µs	70.7 µs	×26
⚡	test_clip_dense_ansi_no_propagate_no_overtype	2,191.7 µs	87 µs	×25
...	...	...	...	...

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_{Comparing jq/libwcwidth-shim-wheels (77fda52) with master (97b4df6)}