SelectableLabel: Use onPressedChanged
OnTapped does not immediately show the context menu when label is rightclicked, breaking QQC2 CI in the process. OnTapped shows the context menu after right click is released.
This changes it to be similar to other elements we have like TextField where right click brings the context menu immediately, instead of on right click button release.
We utilize onPressedChanged, then check if pressed is true, to pop up the context menu immediately.
Edited by Akseli Lahtinen