chore: give command exec funcs ownership of the commands

[reubeno]

No description provided.

[github-actions]

Test Results

    2 files      9 suites   1m 16s ⏱️
  587 tests   587 ✅ 0 💤 0 ❌
1 160 runs  1 160 ✅ 0 💤 0 ❌

Results for commit 7abe307.

[github-actions]

Performance Benchmark Report

Benchmark name	Baseline (μs)	Test/PR (μs)	Delta (μs)	Delta %
clone_shell_object	16.51 μs	16.64 μs	0.13 μs	🟠 +0.81%
eval_arithmetic	0.18 μs	0.18 μs	0.00 μs	⚪ Unchanged
expand_one_string	1.60 μs	1.61 μs	0.01 μs	⚪ Unchanged
for_loop	32.41 μs	32.31 μs	-0.09 μs	⚪ Unchanged
function_call	3.29 μs	3.34 μs	0.05 μs	⚪ Unchanged
instantiate_shell	47.39 μs	48.37 μs	0.98 μs	🟠 +2.07%
instantiate_shell_with_init_scripts	22262.08 μs	23432.66 μs	1170.58 μs	🟠 +5.26%
parse_bash_completion	1659.16 μs	1659.86 μs	0.70 μs	⚪ Unchanged
parse_sample_script	1.75 μs	1.76 μs	0.00 μs	⚪ Unchanged
run_echo_builtin_command	16.25 μs	16.33 μs	0.08 μs	⚪ Unchanged
run_one_external_command	2422.44 μs	2337.12 μs	-85.32 μs	🟢 -3.52%
tokenize_sample_script	2.76 μs	2.92 μs	0.16 μs	🟠 +5.81%

Code Coverage Report: Only Changed Files listed

Package	Base Coverage	New Coverage	Difference
brush-core/src/arithmetic.rs	🟢 98.4%	🟢 98.46%	🟢 0.06%
brush-core/src/builtins/read.rs	🟠 66.27%	🟠 66.47%	🟢 0.2%
brush-core/src/extendedtests.rs	🟠 70.3%	🟠 66.67%	🔴 -3.63%
brush-core/src/interp.rs	🟢 90.72%	🟢 90.71%	🔴 -0.01%
Overall Coverage	🟢 74.7%	🟢 74.66%	🔴 -0.04%

Minimum allowed coverage is 70%, this run produced 74.66%