Merge the sharp edge tagging into `bm_mesh_loops_calc_normals`,
this has the advantage that edge tagging can be performed as part of
walking over each vertices edges - instead of tagging in a separate loop.
Even though this will tag edges twice (once for each vertex),
the computation isn't heavy as it's only calculating a dot-product
between the two face users to compare the angle.
Compared to master this makes `BM_loops_calc_normal_vcos` around 5.68x faster,
with an overall speedup over 2.6x when transforming a high poly mesh.
---
This must be applied on top of D11928.