Add 3-tap-to-hide GUI gesture

[JoseEmilio-ARM]

Description

#672 disabled the click/tap gesture to hide the UI. On smaller screens, particularly when more than 2 lanes of stats are enabled (in Performance samples), the UI takes most of the space, and does not allow to inspect the rendered scene in detail. In this case, it would still be useful to have a way to hide it.

To avoid accidentally hiding the UI when panning the camera, this change re-introduces the gesture, but as a 3-finger tap, so that it is more intentional (a 2-finger tap can still be used to display the debug window in Performance samples).

General Checklist:

Please ensure the following points are checked:

• [x] My code follows the coding style
• [x] I have reviewed file licenses
• [x] I have commented any added functions (in line with Doxygen)
• [x] I have commented any code that could be hard to understand
• [x] My changes do not add any new compiler warnings
• [x] My changes do not add any new validation layer errors or warnings
• [x] I have used existing framework/helper functions where possible
• [x] My changes do not add any regressions
• [x] I have tested every sample to ensure everything runs correctly
• [x] This PR describes the scope and expected impact of the changes I am making

Note: The Samples CI runs a number of checks including:

• [x] I have updated the header Copyright to reflect the current year (CI build will fail if Copyright is out of date)
• [x] My changes build on Windows, Linux, macOS and Android. Otherwise I have documented any exceptions

[gary-sweet]

I can confirm that this builds for me without issue, but I can't test it as I can't run on Android.

[asuessenbach]

Is it correct, that you'd keep *_finger_tap true when you press_down with 2 touch points but press_up with a different number of touch points? Can that happen at all?