Various converter enhancements and bugfixes

[qarmin]

Fixes #62832
Fixes #63291
Fixes #63292
Fixes #63292

Fixed error message about not checking files greater than 500KB(proper message should be that files greater than 4MB are not checked to avoid freezes) #63672

From #63673 I fixed problem with not removing old .shader file - the problem was caused by attempting to remove not-existent file, but also by missing error message in case of trying to remove such file, so I added additional error message to dir_access.h

This PR removes a lot of duplicated code and also add regex cache.

I tried to add const object of type RegExContainer to main converter class, to be able to avoid to pass object of this type to different functions, but I failed to do this due various C++ errors like "Field has incomplete type" or related to RegEx(this probably was my fault).

Supersedes #63299 - not contains patches with RayQueryParameters because looks that this will change in future

Tested with Jetpaca, and after small fixes it works partially

[rburing]

FYI #61918 was merged and allows easier conversion of intersect_ray calls by allowing PhysicsRayQueryParameters to be created with a single static function call.

[akien-mga]

Thanks!