Change return types of trigonometric and hyperbolic imaginary Math functions

[jabraham17]

This PR changes some of the imaginary overloads of trigonometric and hyperbolic functions in the Math module.

This PR deprecates the previously unstable overloads with a config const named useNewImaginaryTrig to switch to the new behavior.

Functions changed in the PR

• proc cos(imag): real
• proc cosh(imag): real
• proc sin(imag): imag
• proc sinh(imag): imag
• proc tan(imag): imag
• proc tanh(imag): imag
• proc asin(imag): imag
• proc atanh(imag): imag

Implements some of the changes outlined in #24506

Testing

• [x] paratest
• [x] paratest + gasnet
• [x] built and checked docs

Reviewed post-merge by @jeremiah-corrado