chore: phpstan:^2.0

[soyuka]

see #7151 (comment)

[soyuka]

@nesl247 I updated and added a baseline with less important checks but there are still about 100 errors that we need to take a look at :/

[nesl247]

@nesl247 I updated and added a baseline with less important checks but there are still about 100 errors that we need to take a look at :/

I'll try to work towards this as I can to help out. Thanks for getting it started!

[VincentLanglet]

I made #7239 @soyuka @nesl247 if you want to take a look.

Every phpstan errors are fixed or ignore with an identifier.
And it will be easier to fix one identifier at a time

[soyuka]

Closing in favor of #7239