Removed GLEW for GLAD, and added sources instead of libs/dlls

[adriengivry]

Description

Removed GLEW for GLAD (core profile 4.5, no extension).
Sources generated from: https://glad.dav1d.de

Review Guidance

Had to fix a bunch of things in OvRendering that was relying on non-standard EXT version of some OpenGL functions (i.e. glGenerateTextureMipmapEXT, and other ones).

GLEW vs GLAD

From our friend ChatGPT

GLEW

• Mature and widely used.
• Great for legacy OpenGL (pre-3.3).
• Requires linking against a library (glew32.lib, etc.).
• Loads all extensions, even unused ones.
• Needs glewInit() after creating an OpenGL context.
• Can have issues with core profile on macOS.
• Less customizable.

GLAD

• Modern, lightweight, and customizable.
• You generate only what you need (version, profile, extensions).
• No need to link any external lib—just include .c and .h.
• Loads only what you specify, making it faster.
• Works well with core profile and newer OpenGL versions.
• Better suited for modern OpenGL (3.3+) and cross-platform development.

Bottom line:

• Pick GLEW for old-school simplicity and legacy support.
• Pick GLAD for modern, efficient OpenGL projects.

To-Do

• ImGui seems to be expecting glew no matter what, so I'll wait for Updated ImGui to v1.91.9 #446 to be merged first
• Test it 😄

Related Issues

Related to #459
Related to #436