Include a central math header file for math constants

[alexander-novo]

As mentioned in #85 it's a little inconvenient to have _USE_MATH_DEFINES littered everywhere we want to use a math constant in.

My suggestion would be to have a file with constants protected with a namespace and something like constexpr real_type PI = M_PI. We can def and undef _USE_MATH_DEFINES around it. In any case, we need one place where we define $\pi$ in the entire code. I would use a separate PR for that, though.

Originally posted by @pelesh in #85 (comment)

[nkoukpaizan]

We now have constants and common math headers that we could use for this.

@alexander-novo @pelesh Any preference on keeping #define _USE_MATH_DEFINES and #include <cmath> versus C++ 20 math constants in std::numbers ?

[alexander-novo]

Going the c++ route and properly templating things based on RealT (which we've already invested 99% of the effort into) gives us benefits in going to things like long double or quad precision in the future. Whereas _USE_MATH_DEFINES doesn't get us that.