Bump Required C++ Standard Version to C++20

[generic-pers0n]

Is your feature request related to a problem? Please describe.
C++ 20 has a couple of things that would allow us to clean up more of our code base, including std::endian and stronger unicode requirements. We might be able to take advantage of some of these features as we clean up parts of Saucedacity's code base.

Describe the solution you'd like
We should bump our minimum required C++ standard to C++ 20.

Describe alternatives you've considered
A good compromise is by making Saucedacity compile in C++ 20. On the other hand, and probably more importantly, we should clean up more of Saucedacity's code base so that bumping the minimum required standard version would make more sense. Currently, we should focus on clean ups first.

Additional context
Compiler support for C++ 20: https://en.cppreference.com/w/cpp/compiler_support/20.

Bumping our minimum required Saucedacity version would also mean having to bump our minimum required compiler versions. For example, this would mean having to bump our minimum required GCC version to 8 instead of 4.9. Similarly, this would mean having to bump our minimum required Visual Studio version to 2019 instead of 2017.