Complete (for our needs) 2D & 3D transformation API. Should be easy to port legacy OpenGL matrix stack-based code to this. Still needs testing.
Ported ortho, frustum, lookAt functions from Viewport FX (rB194998766c65). Kept plenty of Viewport FX code from previous commit.
Stack API and 2D routines ported from Gawain. This version uses BLI_math library so everything is licensed under GPL instead of the usual MPL.
Part of T49450