Overly-strict validation for zero-area triangles in TriangleMesh

[caseyflex]

Describe the bug Validation for zero-area triangles in TriangleMesh is overly strict.

To Reproduce Steps to reproduce the behavior: In the STLImport notebook, in cell [2], a box is imported from an STL file with scale=1 and micron size. When setting scale=1e-3, the geometry fails validation.

Expected behavior The validation should be relaxed so that smaller STL triangles are supported. This is possible in principle, but it requires care to avoid incorrect STL processing.

This issue has come up multiple times.