This is being done by just removing the approximation and lowering to atan2 lib calls later to make the implementation the same as XLA. Note that if the approximation is brought back later, it can be fixed by changing the IR checking `less-than(X, 0)` to `less-than(copysign(X, 1), 0)`
PiperOrigin-RevId: 356253941
Legalize `atan2` analogously to XLA. `atan2` is first reduced to `atan` on the
interval [-1, 1] and subsequently approximated. This CL also adds e2e tests for
trigonometric approximations.
PiperOrigin-RevId: 334794336