Updating Raylib vapis to 6.0-dev and more!

[edwood-grant]

Here is a PR to updated the current Raylib vapis to version 6-dev. Also adding basic samples and adding more raylib libraries.

Here's the list of additions for these vapis:

1. Updated the raylib.vapi and rlgl.vapi files to to version 6.0-dev
2. Updated rini.vapi to version 3.0
3. Added raymath.vapi version 6.0-dev and moved all math related stuff there. This does mean a required import Raymath; to import stuff like Vectors, MArices and Quaternions. I find this ok with me, but let me know if we'd rather keep the basic types in raylib.vapi as well.
4. Added physac.vapi version 1.1
5. Added raygui.vapi version 5.0-dev
6. Added basic examples for some of the vapis and setup the system so it compiles them in a meson subdir.
7. Simple linting pass
8. Updated README.md to reflect these changes.

Note: This is for Raylib 6.0-dev, which is still in development... but I understand, and expect version 6.0 it to be released very soon, probable between March and April (as far as I understand, the milestone is in march and they are already checking if the samples work OK, so I assume its going to be very soon).

So this should be already up to date with the latest Raylib version once it releases. Maybe it'll need another pass once an official version launches.

Future work would be:

1. Adding some missing libraries (essentially rpng and rres).
2. More examples!

Let me know if this looks good to update the whole Vapis!

Thanks,