Refactors the accessibility providers (ScreenInfoUiaProvider and UiaTextRange) into a better separated model between ConHost and Windows Terminal.
ScreenInfoUiaProviderBase and UiaTextRangeBase are introduced. ConHost and Windows Terminal implement their own versions of ScreenInfoUiaProvider and UiaTextRange that inherit from their respective base classes.
WindowsTerminal's ScreenInfoUiaProvider --> TermControlUiaProvider