Fix #139753: Discontinuity in mesh tangent without UV map

when there is no uv, we call the function `map_to_sphere()` to create
temporary uv for computing the tangent. It could happen that a triangle
has vertices with the u coordinates going across the line where u wraps
from 1 to 0. In this case, just computing the difference of the u
coordinates results in the wrong triangle area.

To fix this problem, we compute distance in toroidal (wrap around)
space.

This is safe for coordinates generated by `map_to_sphere()` function,
because it is not supposed to map the positions of a triangle to u
coordinates that span larger than 0.5.

Pull Request: https://projects.blender.org/blender/blender/pulls/139880

tests/python/eevee_render_tests.py

@@ -43,8 +43,6 @@ BLOCKLIST = [
 ]
 
 BLOCKLIST_METAL = [
-    # Blocked due to difference in tangent space calculation (to be fixed).
-    "tangent_no_uv.blend",
     # Blocked due to difference in volume lightprobe bakes (to be fixed).
     "clamp_.*.blend",
     "shadow_all_max_bounces.blend",