Cleanup: everything in `components/misc/constants.hpp` should be constexpr

Most of the constants in components/misc/constants.hpp are declared in a wrong way:

1. All constants defined in a header should be constexpr, otherwise it will be included to the binary several times. std::string can not be constexpr, so it can changed into std::string_view.
2. static shouldn't be used in headers for non-class-member variables.