Modern GL best practices layer

[Jake Ryan]

A way to "soft deprecate" old-but-not-ancient GL functionality. I'm open to suggestions as well.

• Warn if non-DSA functions are used
• Warn if non-storage (TextureStorage, BufferStorage) functions are used
• Warn if VertexAttribPointer is used (prefer VertexAttribFormat, VertexArrayVertexBuffer, etc.)
• Warn if ActiveTexture is used (prefer BindTextureUnit)

Debatably:

• Warn if resource binding indices are set via uniform rather than setting it in the shader with binding = #
• Warn if uniforms are used at all (prefer uniform buffers)
• When drawing, warn if a texture object is bound to a texture binding, but no sampler object is (avoid using the built-in texture sampler state)

This is somewhat related to #1.