feat: implement support for ;;& and ;& in case items

[reubeno]

Implements support for bash extensions to case item terminators: ;;& and ;&.

Fixes one of the issues tracked by #222.

[github-actions]

Test Results

  2 files    9 suites   1m 2s ⏱️
481 tests 481 ✅ 0 💤 0 ❌
953 runs  953 ✅ 0 💤 0 ❌

Results for commit 5d794f4.

[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	59.77 μs	59.40 μs	-0.37 μs	⚪ Unchanged
instantiate_shell_with_init_scripts	30386.84 μs	30436.68 μs	49.84 μs	⚪ Unchanged
parse_bash_completion	2769.17 μs	2759.15 μs	-10.03 μs	⚪ Unchanged
parse_sample_script	4.28 μs	4.21 μs	-0.07 μs	⚪ Unchanged
run_echo_builtin_command	88.81 μs	89.57 μs	0.76 μs	⚪ Unchanged
run_one_builtin_command	107.68 μs	108.18 μs	0.50 μs	⚪ Unchanged
run_one_external_command	2052.96 μs	1986.42 μs	-66.55 μs	🟢 -3.24%
run_one_external_command_directly	1010.26 μs	1005.66 μs	-4.60 μs	⚪ Unchanged

Code Coverage Report: Only Changed Files listed

Package	Base Coverage	New Coverage	Difference
brush-core/src/interp.rs	🟢 90.02%	🟢 90.13%	🟢 0.11%
brush-core/src/jobs.rs	🔴 37.23%	🔴 42.42%	🟢 5.19%
brush-core/src/patterns.rs	🟢 97.77%	🟢 97.78%	🟢 0.01%
brush-core/src/shell.rs	🟢 78.11%	🟢 78.54%	🟢 0.43%
brush-parser/src/ast.rs	🔴 25.66%	🔴 25.35%	🔴 -0.31%
brush-parser/src/parser.rs	🟢 99.74%	🟢 99.75%	🟢 0.01%
brush-shell/src/main.rs	🟢 90.2%	🟢 90.85%	🟢 0.65%
Overall Coverage	🟢 73.33%	🟢 73.45%	🟢 0.12%

Minimum allowed coverage is 70%, this run produced 73.45%