tests: add an env variable bench for testing

[art049]

No description provided.

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #89 will degrade performances by 7.82%

_{Comparing cod-658-i-cannot-pass-an-env-variable-to-the-thing-running (eb092d6) with main (d223cd8)}

Summary

❌ 7 regressions
✅ 161 untouched benchmarks
🆕 1 new benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	bench_array1[42]	1 µs	1.1 µs	-5.36%
❌	bench_array2[42]	1 µs	1.1 µs	-5.36%
❌	init_array[42]	1 µs	1.1 µs	-5.36%
❌	mut_borrow	866.7 ns	895.8 ns	-3.26%
🆕	print_env_hello	N/A	8 µs	N/A
❌	recursive[10]	903.3 ns	932.5 ns	-3.13%
❌	instant	343.9 ns	373.1 ns	-7.82%
❌	system_time	345.3 ns	374.4 ns	-7.79%

[codspeed-hq]

CodSpeed Walltime Performance Report

Merging #89 will degrade performances by 48.73%

_{Comparing cod-658-i-cannot-pass-an-env-variable-to-the-thing-running (1b8f549) with main (d223cd8)}

Summary

⚡ 10 improvements
❌ 7 regressions
✅ 127 untouched benchmarks
🆕 1 new benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	build_vec	215 ns	201 ns	+6.97%
⚡	large_drop	181.8 µs	166.9 µs	+8.91%
⚡	large_setup	12 ns	11 ns	+9.09%
⚡	from_elem[2048]	249 ns	237 ns	+5.06%
⚡	from_elem[8192]	489 ns	471 ns	+3.82%
❌	bench_array1[4]	3.2 µs	3.9 µs	-18.8%
❌	bench_array2[4]	3.2 µs	3.9 µs	-18.8%
⚡	init_array[1000]	6.8 µs	1.7 µs	×3.9
❌	init_array[4]	3.2 µs	3.9 µs	-18.8%
🆕	print_env_hello	N/A	1.9 µs	N/A
⚡	generate_combinations[8]	3.2 µs	3.1 µs	+3.1%
❌	graph_coloring[5]	3.9 µs	4 µs	-3.01%
❌	rat_in_maze[6]	2.9 µs	5.6 µs	-48.73%
❌	add_two_integers[(255, 255)]	3.4 µs	5.1 µs	-33.83%
❌	add_two_integers[(42, 13)]	3.4 µs	5.1 µs	-33.83%
⚡	sleep_100ns	54.4 µs	42.2 µs	+29.09%
⚡	sleep_100us	157.7 µs	140.2 µs	+12.46%
⚡	sleep_1ns	57.6 µs	24.6 µs	×2.3