[BUILD] Update Makefile with `MODE` variable that lets user combine multiple targets + more features #698

Job	Run time
Compilation Test (gcc)	29s
Compilation Test (clang)	31s
Compilation Test (clang-12)	36s
Prepare Test Matrix	2s
Combine Compilation Test Results	1s
Regression Test (b, Bonus Part) / Bonus Part	1m 15s
Regression Test (d, Hardcore) / Hardcore	41s
Regression Test (m, Mandatory Part) / Mandatory Part	1m 4s
Regression Test (ne, Empty Env) / Empty Env	33s
Memory Leak Test (1_groups.sh)	37s
Memory Leak Test (1_operators.sh)	34s
Memory Leak Test (1_wildcards.sh)	50s
Memory Leak Test (2_correction.sh)	2m 28s
Memory Leak Test (3_subshell.sh)	56s
Memory Leak Test (8_syntax_errors.sh)	1m 56s
Memory Leak Test (9_go_wild.sh)	52s
Memory Leak Test (leaks.sh)	27s
Memory Leak Test (0_compare_parsing.sh)	1m 16s
Memory Leak Test (10_parsing_hell.sh)	1m 47s
Memory Leak Test (11_expansion.sh)	30s
Memory Leak Test (1_builtins_cd.sh)	1m 11s
Memory Leak Test (1_builtins_echo.sh)	1m 31s
Memory Leak Test (1_builtins_env.sh)	35s
Memory Leak Test (1_builtins_exit.sh)	1m 7s
Memory Leak Test (1_builtins_export.sh)	1m 1s
Memory Leak Test (1_builtins_pwd.sh)	1m 16s
Memory Leak Test (1_builtins_unset.sh)	56s
Memory Leak Test (1_pipelines.sh)	1m 17s
Memory Leak Test (1_redirs.sh)	2m 0s
Memory Leak Test (1_scmds.sh)	57s
Memory Leak Test (1_variables.sh)	1m 23s
Memory Leak Test (2_correction.sh)	2m 8s
Memory Leak Test (2_path_check.sh)	44s
Memory Leak Test (8_syntax_errors.sh)	1m 8s
Memory Leak Test (9_go_wild.sh)	45s
Memory Leak Test (1_segfault.sh)	2m 5s
Memory Leak Test (10_no_env.sh)	56s
Combine Regression Test Results	1s
Combine Memory Leak Test Results	1s
	38m 27s

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