More C++ tweaks and changes

[grendello]

Continued effort to restructure our native C++ runtime, introducing
C++23 features as well as turning as many classes into static ones since
we don't really have objects that need to be created and destroyed during
lifetime of the application:

• Replace abort_if* preprocessor macros with templated functions. This
  gives us better type safety. Instead using variadic arguments, we now
  provide overloads which take either a plain string without placeholders
  or a lambda function to format the message string on demand.
• More std::string_view for literal strings
• More functions decorated with noexcept (this is going to be important
  once exceptions are enabled in the future)
• Remove some unused code.