UI Automation in Windows Console: Remove "Text area", replace isAtLeastWin10, and code cleanup (#9761)
* isAtLeastWin10 -> isWin10(atLeast = True)
* winConsoleUIA.winConsoleUIA -> winConsoleUIA.WinConsoleUIA for consistency.
* Further renaming of winConsoleUIA -> WinConsoleUIA, and once again explicitly clear the word buffer when flushing queued chars.
* Comments.