More specific superglobals feedback update

[kkmuffme]

Fix #8559
Fix #8556

I think the $_FILES superglobal type is correct now, but absolute crap due to #8516

Ideally we would have 4 distinct array types for it like:

array<never, never> (= array{})
|array{error: int<0, 8>, name: string, size: int<0, max>, tmp_name: string, type: string}
|array{error: non-empty-list<int<0, 8>>, name: non-empty-list<string>, size: non-empty-list<int<0, max>>, tmp_name: non-empty-list<string>, type: non-empty-list<string>}
|array<string, array{error: int<0, 8>, name: string, size: int<0, max>, tmp_name: string, type: string}>
|array<string, array{error: non-empty-list<int<0, 8>>, name: non-empty-list<string>, size: non-empty-list<int<0, max>>, tmp_name: non-empty-list<string>, type: non-empty-list<string>}>

Feel free to make any changes necessary before merging, I won't have time until next weekend though.

[VincentLanglet]

For the record

• Phpunit cast 'false' and 'true' to a boolean.
• Symfony support using APP_DEBUG=0 or APP_DEBUG=1 in the .env file.
  So the best way to represent this is bool|string and force people to cast to bool.

[orklah]

Thanks!