Tests: Use absolute delta value when comparing against tolerance

[mrxz]

Description

Some of the equals functions in the unit tests (e.g. matrixEquals4) incorrectly compared signed delta values to the tolerance threshold, instead of absolute values. As a result differences where b > a would never "exceed" the tolerance and always pass.

Additionally the bufferAttributeEquals failed to actually compare the contents of the attributes. After resolving this issue, it became clear that the computeVertexNormals (indexed) test was broken. I tried to find out what the original intention of the test was but it seems it was introduced in a broken state in #12354. As such, I've taken the liberty to tweak it so that:

• There are only 6 vertices instead of 7 (ensuring non-indexed computeVertexNormals can actually compute all values)
• The index buffer uses the same two triangles as non-indexed, but in a counter-clockwise order, so that normals get flipped.

This contribution is funded by Fern Solutions