This patch adds support for PBVH drawing in EEVEE.
Notes:
# PBVH_FACES only. For Multires we'll need an API to get/cache attributes. DynTopo support will be merged in later with sculpt-dev's DynTopo implementation.
# Supports vertex color and UV attributes only; other types can be added fairly easily though.
# Workbench only sends the active vertex color and UV layers to the GPU.
# Added a new draw engine API method, DRW_cdlayer_attr_aliases_add. Please review.
# The vertex format object is now stored in the pbvh.
Reviewed By: Clément Foucault & Brecht Van Lommel & Jeroen Bakker
Differential Revision: https://developer.blender.org/D13897
Ref D13897
After this commit, all mesh data extraction and drawing code is in C++,
including headers, making it possible to use improved types for future
performance improvements and simplifications.
The only non-trivial changes are in `draw_cache_impl_mesh.cc`,
where use of certain features and macros in C necessitated larger
changes.
Differential Revision: https://developer.blender.org/D15088
