Remove usages of old safe math

There are approximately 79 uses of old safe math. (a.k.a. the LongAdd, ShortAdd, and friends from intsafe.h).

This task represents removing them and transitioning them to an appropriate safe/saturating math function from the chromium safe math library introduced in #4144.

After removing usages of the old safe math functions, also remove the intsafe.h header.

Files with old safe math as of this writing:

• TerminalControl: TSFInputControl.cpp
• TerminalCore: TerminalDispatch.cpp
• TerminalCore: TerminalSelection.cpp
• Host: directio.cpp
• RendererGdi: invalidate.cpp
• RendererGdi: math.cpp
• RendererGdi: paint.cpp
• RendererVt: paint.cpp
• TerminalAdapter: adaptDispatch.cpp
• Types: viewport.cpp
• Types: WindowUiaProviderBase.cpp