[build] only include rglfw.c for glfw platform

It looks like raylib doesn't require rglfw.c if you're using the RGFW
backend.  I'm guessing the same is true for SDL but I haven't tested.
Excluding this one file brings the raylib library down from 6.9 MB to
6.3 MB for RGFW.

However, one of the examples requires the symbols from rglfw.c,
to accomodate this I added a function that will check whether raylib has
already included rglfw and if not include it for that one example.

Avoid divide by 0 in core_custom_frame_control example

[build] remove examples/build.zig, incorporate into main build.zig

Removes the second build.zig in the examples directory and incorporates it
into the main build.zig. This gives the zig build system the data needed to
know if the raylib library needs to be rebuilt when running any example.

[rcore] fix: TRACELOG upon successfully changing directory

InitWindow() prints CWD during initialization,
but ChangeDirectory() does not, which is quite confusing when you start
messing with CWD. Now said function should log similar message.

I'm sorry... I did not detect this change was breaking batching... :(

[examples] use logarithmic zoom scaling in 2d camera examples

This compensate for slower zoom speed due to log scaling

The support for the scissor test has been implemented for clearing as well as for triangle clipping.
The implementation for lines and points is still missing.

I also removed the 2D clipping of lines that used the Cohen-Sutherland algorithm, opting instead to always use the Liang-Barsky algorithm in all cases.
This simplifies the implementation, and the 2D version would have caused issues when interpolating vertices in the future if we want to implement additional features.

- `glDepthMask`
- `glColorMask`

Add early return when angles are equal in DrawCircleSector and DrawCircleSectorLine functions.

Prevents unnecessary work and division by zero (when segments=0) in DrawCircleSector/DrawCircleSectorLines when startAngle equals endAngle, matching existing behavior in DrawRing/DrawRingLines.

Several depth and color formats have been added for the framebuffer.

8-bit, 16-bit, and 24-bit formats are now available for depth.

RGB 8-bit (332), RGB 16-bit (565), and RGB 24-bit (888) formats are now available for color.

Alpha support is no longer present for the framebuffer at the moment, but it can easily be restored by adding the formats and reinterpolating the alpha in the areas that do not perform color blending.

Additionally, this commit brings performance improvements.