Removed unused graphie::findPointFromAngle

Summary:
Removes graphie::findPointFromAngle, which (a) was no longer used,
(b) wasn't implemented using kvector utilities, and (c) should be
replaced by something in kpoint if needed again.

It was added for transformer rotation tool, where it has since been replaced
by kvector utilities.

Test Plan:
grep for findPointFromAngle
ensure transformer rotation tool still works

Auditors: alex