C++ compiler support v2

[sakgoyal]

Redoing #5232 because I messed up the force push.

Allow C++ compilers to compile this code without separately linking as a C library.

Changes:

• Backport RGFW unicode fix
  • ColleagueRiley/RGFW@0ebeb37
• Add C-style casting where necessary
• Fix a initializer list being in the wrong order (C++ requires declaration order)
• GLFW currently has issues with cross compiling so I am using RGFW for now
  • Clang++ build for windows glfw/glfw#2777
• Change C Aggregate initializer to C++ default initializer.

TODO:

• Do not modify external libraries. update them instead
  • jar_* is ok to update. Managed by raysan5
• C++ = {0}
  • maybe consider -ftrivial-auto-var-init=zero or something instead

[raysan5]

@sakgoyal Added some review comments, just noticed that most are already listed on the TODO. Please, let me know when ready to merge. Thanks!

[sakgoyal]

I don't want to update some of the dependencies. Many of them seem to introduce breaking changes that need more work to get working again that feels out of scope for this PR.

All workflows passed:
https://github.com/sakgoyal/raylib/actions

[raysan5]

@sakgoyal added some minor tweaks to review

[sakgoyal]

There could be another CI action for checking formatting (NOT a commit hook).

It would reduce a lot of back and forth.

[raysan5]

@sakgoyal sure! but it needs to be coded!