[Flang] Lower atan, sinh, cosh intrinsics

[Flang] Lower atan, sinh, cosh intrinsics

The intrinsic computes the tan and hyperbolic sin, cosine values. By
default they are lowered to runtime calls to the math library. Not all
types are supported currently. The generic and llvm lowering does not
lower floating point types with kind greater than 8, the llvm lowering
does not support the complex types.

Note: tanh is not present in fir-dev hence ignoring for now. We can add
support after upstreaming is complete. sin and cos will come in separate
patches since they have llvm intrinsic lowering.

This is part of the upstreaming effort from the fir-dev branch in [1].
[1] https://github.com/flang-compiler/f18-llvm-project

Reviewed By: PeteSteinfeld

Differential Revision: https://reviews.llvm.org/D122264

Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>
Co-authored-by: William Moses <gh@wsmoses.com>