Improve DEBUG flag

[RobinMalfait]

This PR will improve the parsing of the DEBUG flag.
Currently we only check if you provided a DEBUG flag and that you didn't provide the value 0. This worked so far, but it's time to improve upon this.

There is the debug package which is used by many applications and includes some conventions: https://github.com/debug-js/debug#conventions

So now we will ensure that take care of the following cases:

Value	Debug enabled
'true'	true
'1'	true
'false'	false
'0'	false
'*'	true
'tailwind'	true
'tailwind:*'	true
'tailwindcss'	true
'tailwindcss:*'	true
'other,tailwind'	true
'other,tailwind:*'	true
'other,tailwindcss'	true
'other,tailwindcss:*'	true
'other,-tailwind'	false
'other,-tailwind:*'	false
'other,-tailwindcss'	false
'other,-tailwindcss:*'	false
'-tailwind'	false
'-tailwind:*'	false
'-tailwindcss'	false
'-tailwindcss:*'	false

Added a bit of code but the good part is that this only runs once at the beginning so shouldn't be too bad.

Fixes: #6769

[mustafa0x]

Is there a config option to tell tailwind to ignore DEBUG=1? I have it in my .env for my backend, but tailwind picks it up, since I'm using direnv, which automatically loads .env files.