Fix Qt6.2 compatibality issues

[uqlidi]

fix the compatibility of the folder dialog component with qt6.2 that causes a failure with ubuntu22.04

Also, added ubuntu22.04 to the CI matrix

fix #783

[hebasto]

CI fails:

qrc:/test/qml/tst_activity.qml:28:9: Type Activity unavailable 
             Activity { 
             ^
qrc:/qml/pages/wallet/Activity.qml:636:17: Type ContextMenuPicker unavailable 
                     ContextMenuPicker { 
                     ^
qrc:/qml/controls/ContextMenuPicker.qml:5:25: Expected token `;' 
     pragma ComponentBehavior: Bound 
                             ^

Errors while running CTest

50% tests passed, 1 tests failed out of 2

Total Test time (real) =  13.70 sec

The following tests FAILED:
	  2 - bitcoinqml_qmltests (Failed)

[hebasto]

Converting to draft until CI is green.

[uqlidi]

CI fails:

qrc:/test/qml/tst_activity.qml:28:9: Type Activity unavailable 
             Activity { 
             ^
qrc:/qml/pages/wallet/Activity.qml:636:17: Type ContextMenuPicker unavailable 
                     ContextMenuPicker { 
                     ^
qrc:/qml/controls/ContextMenuPicker.qml:5:25: Expected token `;' 
     pragma ComponentBehavior: Bound 
                             ^

Errors while running CTest

50% tests passed, 1 tests failed out of 2

Total Test time (real) =  13.70 sec

The following tests FAILED:
	  2 - bitcoinqml_qmltests (Failed)

pragma ComponentBehavior: Bound was introduced in Qt 6.4 (read: https://doc.qt.io/qt-6/qtqml-documents-structure.html), so it fails to parse under our documented Qt 6.2 minimum. On 6.2 the QML parser reports Expected token ';' at the pragma line. This is what the new Ubuntu 22.04 / Qt 6.2 CI job caught.

There's no pre-6.4 language equivalent of the pragma, so we can't make it version-conditional cleanly (QML has no preprocessor, and gating it via build-time file generation is more machinery than a single lint line justifies).

Removing it is safe because the pragma is only advisory here.

[uqlidi]

Ready for review. All issues with Ubuntu 22.04 were solved

[uqlidi]

@hebasto ping

[uqlidi]

@hebasto could you take a look at this when you have the time, please?

[johnny9]

ACK f1796dd