Add OpenGL model loading and font rendering example

[lzzrhx]

This example includes a basic GLFW / OpenGL set up with a basic lit shader, font rendering, and a cgltf function for model loading. The included font.png is based on ToshibaSat 8x16. I am not very familiar with how to include licenses properly, but gave it a go in the included LICENSE file.

Checklist before submitting:

• This example has been added to .github/workflows/check.yml (for automatic testing)
• This example compiles cleanly with flags -vet -strict-style -vet-tabs -disallow-do -warnings-as-errors
• This example the naming and style convention: https://github.com/odin-lang/examples/wiki/Naming-and-style-convention (exceptions can be made for ports of examples that need to match 1:1 to the original source).
• By submitting, I understand that this example is made available under these licenses: Public Domain and Odin's zlib license. Only for third-party dependencies are other licenses allowed.