Multi parser setup V2

[AntoineBastide47]

This PR upgrades the multi parser setup and add more QoL functionalities:

1. Adding a new supported language is easier, just add a new entry in LanguageData.hpp (the parser still needs to be written)
2. All detected languages are parsed in repositories by finding all file extensions and checking if a language is present
3. Single language parsing is still available using --language <language>, and custom file extensions can also be passed --extensions <ext1,ext2,...>
4. Added a proper usage string to the parser cli.
5. Moved all logged statistics to markdown files in result/<repo_path>/ and added per language stats in result/<repo_path>/<language>/

P.S: The first version of the multi parser still needs to be commited so this is currently a draft, do not review