[BasicUI] Fix slider behaviour and implement two different modes

[lolodomo]

Fix #2525 Also related to openhab/openhab-core#4084 and openhab/openhab-core#3430

Two behaviour modes are now supported.

• If releaseOnly parameter is set, the new value is sent to the item only when the slider is released.
• If releaseOnly parameter is not set, new values are sent to the item while moving the slider. Events are sent at a certain frequency, this frequency is defined by the sendFrequency parameter if set or every 200 ms by default. Event is not sent when the value is is unchanged (when stopping the move but keeping the mouse pressed).

The brightness slider of the colorpicker widget is also updated to send regular new color commands when moving the slider.

Signed-off-by: Laurent Garnier lg.hc@free.fr

[lolodomo]

Change tested with success using Firefox, Chrome and Edge on Windows 10 and using Chrome on an Android phone.

Note that the previous implementation tries to handle browsers not respecting the standard* but with problems with all browsers respecting this standard. I can"t test with Safari browser but I read that Safari respects the standard so it should work well.

*Expected behaviour for a browser is to trigger "input" events when the slider is moving but not "change" events. "change" event should be triggered only when the slider is finally released. I read that 10 years ago, browsers like Internet Explorer were triggering "change" events while the slider was moving.