deedbee971
Part of #116901. This file contains the creation of four different UV edit index buffers: triangles, lines, points, and face dots. The main changes are about making it clearer when faces are skipped. Other than that, changes are faily extensive but straightfoward. In a few places some parts of existing loops have been split out and parallelized, but the bulk of the work for each IBO remains largely single threaded.