0032433: Visualization, TKService - introduce Wasm_Window implementing Aspect_Window...

0032433: Visualization, TKService - introduce Wasm_Window implementing Aspect_Window interface using Emscripten SDK

Introduced Wasm_Window implementing Aspect_Window interface.

Aspect_WindowInputListener has been extended by touch input callbacks (moved from AIS_ViewController),
which now implements redirection of single taps to UpdateMouseClick().

AIS_ViewController::FetchNavigationKeys() now requests more frames even if Delta is zero,
but navigation keys are pressed - indicated by a new flag AIS_WalkDelta::IsDefined().

Fixed missing implementation of Xw_Window::DisplayConnection() getter.
The property has been moved to the base class Aspect_Window.

Removed unused Aspect_Convert.hxx.

DRAWEXE targeting Wasm:
- added exposing of FS interface so that it is possible uploading/downloading files to/from emulated file system on JavaScript level;
- added printer redirecting messages to Module.printMessage callback accepting message gravity;
- Run_Appli() now skips std::cin when Module.noExitRuntime is set.