fix: assorted completion-related issues

[reubeno]

• Unquote the token-to-be-completed passed into compgen
• Support multiple-options-in-one-token in getopts (e.g., -abc as shorthand for -a -b -c)
• Initialize OPTIND, OPTERR in each newly constructed shell.
• Fix bug in printf hack for %q and ~%q.
• Don't filter out file/dir completions whose prefixes don't match the token-being-completed (e.g., for ~ et al.).
• For file/dir completions, basic-expand the token-to-be-completed (we formerly did this higher up the stack).
• Express compatibility with a slightly newer version of bash (5.2.x).
• Re-enable some previously disabled tests.

[github-actions]

Test Results

  2 files    9 suites   1m 5s ⏱️
493 tests 493 ✅ 0 💤 0 ❌
975 runs  975 ✅ 0 💤 0 ❌

Results for commit a1a1c6a.

♻️ This comment has been updated with latest results.

[github-actions]

Performance Benchmark Report

Benchmark name	Baseline (μs)	Test/PR (μs)	Delta (μs)	Delta %
expand_one_string	3.42 μs	3.42 μs	0.00 μs	⚪ Unchanged
instantiate_shell	60.55 μs	59.71 μs	-0.84 μs	⚪ Unchanged
instantiate_shell_with_init_scripts	30366.85 μs	30618.42 μs	251.57 μs	🟠 +0.83%
parse_bash_completion	2768.72 μs	2801.54 μs	32.83 μs	🟠 +1.19%
parse_sample_script	4.26 μs	4.25 μs	-0.00 μs	⚪ Unchanged
run_echo_builtin_command	90.33 μs	89.64 μs	-0.69 μs	⚪ Unchanged
run_one_builtin_command	107.92 μs	109.23 μs	1.31 μs	⚪ Unchanged
run_one_external_command	1982.78 μs	1980.10 μs	-2.69 μs	⚪ Unchanged
run_one_external_command_directly	1011.24 μs	1006.63 μs	-4.62 μs	⚪ Unchanged

Code Coverage Report: Only Changed Files listed

Package	Base Coverage	New Coverage	Difference
brush-core/src/builtins/complete.rs	🔴 22.11%	🔴 21.57%	🔴 -0.54%
brush-core/src/builtins/getopts.rs	🟢 95.9%	🟢 94.81%	🔴 -1.09%
brush-core/src/builtins/printf.rs	🟢 92%	🟢 93.88%	🟢 1.88%
brush-core/src/completion.rs	🔴 18.63%	🔴 19.93%	🟢 1.3%
brush-core/src/shell.rs	🟢 78.11%	🟢 78.52%	🟢 0.41%
brush-shell/src/main.rs	🟢 90.2%	🟢 90.85%	🟢 0.65%
Overall Coverage	🟢 73.53%	🟢 73.55%	🟢 0.02%

Minimum allowed coverage is 70%, this run produced 73.55%