Handle *-rotate for point-placed symbols.

[ChrisLoer]

Fixes issue #6075 -- or at least fixes what I think is the chief complaint remaining there: that the combination of *-offset and *-rotate doesn't work for point labels.

This PR does not fix:

• Collision detection for point symbols with *-rotation-alignment: map (Collision boxes don't account for symbol-placement:point/rotation-alignment: map #4861)
• Collision detection or for line-placed symbols with *-offset (and/or *-rotate): (Respect text-offset in line-placed symbol collision handling #4798)
• Combination with icon-text-fit: (Icon collision boxes don't account for icon-text-fit #5641)

Launch Checklist

• briefly describe the changes in this PR
• write tests for all new functionality
• post benchmark scores
• manually test the debug page

/cc @anandthakker @ansis

[ChrisLoer]

One of the render tests kept failing because the collision box would draw slightly differently on the CI machine (I think this is just built into the variation in gl.LINES implementations). The part that was failing was not actually the thing under test (it was just a reference to show where the origin of the offset was), so I just removed it.

An alternative solution would be to write the tests as query tests, but I prefer render tests because they're more visual/simpler to understand.

[anandthakker]

Nice un-overcomplication of the problem 😄