Basic implementation of DEBUG trap, help improvements

[reubeno]

No description provided.

[github-actions]

Performance Benchmark Report

Benchmark name	Baseline (ns)	Test/PR (ns)	Delta (ns)	Delta %
expand_one_string	3352 ns	3449 ns	+97 ns	🟠 +2.89%
instantiate_shell	64196 ns	64716 ns	+520 ns	🟠 +0.81%
instantiate_shell_with_init_scripts	46863494 ns	47557097 ns	+693603 ns	🟠 +1.48%
parse_bash_completion	6534282 ns	6564619 ns	+30337 ns	🟠 +0.46%
parse_sample_script	10690 ns	10802 ns	+112 ns	🟠 +1.05%
run_echo_builtin_command	104263 ns	106725 ns	+2462 ns	🟠 +2.36%
run_one_builtin_command	121802 ns	121972 ns	+170 ns	🟠 +0.14%
run_one_external_command	1815982 ns	1816381 ns	+399 ns	🟠 +0.02%
run_one_external_command_directly	1024188 ns	1028863 ns	+4675 ns	🟠 +0.46%

Code Coverage Report

Package	Base Coverage	New Coverage	Difference
cli.src	🟠 73.95%	🟠 73.33%	🔴 -0.62%
interactive-shell.src	🟢 76.02%	🟢 76.02%	⚪ 0%
parser.src	🟢 85.88%	🟢 85.88%	⚪ 0%
shell.src	🟢 81.29%	🟢 80.42%	🔴 -0.87%
shell.src.builtins	🟠 70.61%	🟠 73.53%	🟢 2.92%
Overall Coverage	🟢 79.91%	🟢 80.05%	🟢 0.14%

Minimum allowed coverage is 0%, this run produced 80.05%