New header is introduced to gradually move our new string-related helper
functions in there (out of support header).
Rewrite starts_with function, as it was triggering debug assertion
in MSVC: "Expression: cannot seek string iterator after end" (when
calling starts_with("opengl", "auto").
Limit starts_with interface only to our actual usecases, such as:
starts_with("prefix", text)
This way we can save time on calculating string length of hardcoded
prefix.
Drop ends_with function, as we don't use it any more - the code using it
was refactored some time ago.
