Add code linting using Laravel Pint

[AndrewKostka]

Bug: T394986

[outdooracorn]

Looking through the changes this linting applies, I'm happy with most of them. I would vote to change a few things:

1. headsDownCamelCase instead of snake_case for function names - this should remove a lot of changes
2. keep function's opening brace ({) on the same line as the function definition
3. keep a space around the string concatenation operator (.) - I think it makes it look less like a full stop and more like an operator.

[AndrewKostka]

Let's use .git-blame-ignore-revs to ignore the resulting squash commit.

[AndrewKostka]

For GitHub, see https://docs.github.com/en/repositories/working-with-files/using-files/viewing-and-understanding-files#ignore-commits-in-the-blame-view

[rosalieper]

LGTM!