CI: Automate formatting checks for C, Shell, and Python

[G36maid]

To keep the codebase clean and consistent with the rules in CONTRIBUTING.md
we should add automatic format checks for all supported languages.

Tools:

• C / C++: clang-format
• Shell: shfmt
• Python: black

[jserv]

You can follow rv32emu:

• check-format
• check-newline