Add regression test for triangulate faces

Basic test for `quads_convert_to_tris`

As the operator name in blender is different from the bpy name, the operator
name in blender was opted in terms of the blend file collection name as well
as the test name. This was done so that new developers in the future can
easier understand which operator this corresponds to. Although it might be
better to change this to the bpy name so as to be consistent with the rest
of the codebase.

Updated blend file `lib/tests/modeling/operators.blend` has been
committed as rBL63101.

Reviewed By: zazizizou, mont29

Differential Revision: https://developer.blender.org/D16072

tests/python/operators.py

@@ -480,6 +480,12 @@ def main():
                                                     "use_center": True}, "VERT", {i for i in range(5)})],
         ),
 
+        # Triangulate Faces
+        SpecMeshTest(
+            "Triangulate Faces", "testCubeTriangulate", "expectedCubeTriangulate",
+            [OperatorSpecEditMode("quads_convert_to_tris", {}, "FACE", {i for i in range(6)})],
+        ),
+
         # Tris to Quads
         SpecMeshTest(
             "TrisToQuads", "testPlanesTrisToQuad", "expectedPlanesTrisToQuad",