fix #25882
Created AccessibleToolButton class.

This class allows tabbing throught the tool bar and changes
the button's icon color when the focus is gained by tabbing.
It also allows triggering the default action of the button by
pressing Enter or Return key.
	modified:   mscore/CMakeLists.txt
	new file:   mscore/accessibletoolbutton.cpp
	new file:   mscore/accessibletoolbutton.h
Added tabbing support for some* buttons.

*I've added tabbing support just for buttons that open dialogs which
already have accessibility support and for buttons that are used
for score playback.
	modified:   mscore/musescore.cpp
Removed most of the unaccessible objects from tabbing order, 5 more remaining.

I wasn't able to find those 5 remaining.
	modified:   mscore/musescore.cpp
Removed 4 more objects from the tabbing order. 1 remaining.

I have removed 4 more objects that are at this point irevelent from
an accessibility point of view, or do not provide accessibility support
yet.
	modified:   mscore/accessibletoolbutton.cpp
	modified:   mscore/importmidi_panel.ui
	modified:   mscore/musescore.cpp
	modified:   mscore/scoretab.cpp
	modified:   mscore/scoreview.cpp
Created AccessibleToolButton class.

This class allows tabbing throught the tool bar and changes
the button's icon color when the focus is gained by tabbing.
It also allows triggering the default action of the button by
pressing Enter or Return key.
	modified:   mscore/CMakeLists.txt
	new file:   mscore/accessibletoolbutton.cpp
	new file:   mscore/accessibletoolbutton.h
Added tabbing support for some* buttons.

*I've added tabbing support just for buttons that open dialogs which
already have accessibility support and for buttons that are used
for score playback.
	modified:   mscore/musescore.cpp
Removed most of the unaccessible objects from tabbing order, 5 more remaining.

I wasn't able to find those 5 remaining.
	modified:   mscore/musescore.cpp
Removed 4 more objects from the tabbing order. 1 remaining.

I have removed 4 more objects that are at this point irevelent from
an accessibility point of view, or do not provide accessibility support
yet.
	modified:   mscore/accessibletoolbutton.cpp
	modified:   mscore/importmidi_panel.ui
	modified:   mscore/musescore.cpp
	modified:   mscore/scoretab.cpp
	modified:   mscore/scoreview.cpp
Removed Return key from being a shorcut for the system break action.
It is now treated as a KeyPressEvent in ScoreTab.cpp.

Now the widget that has focus will receive the event. Before, even
if a widget wanted to do something when return Key was pressed, it
was unable to do that, because shortcuts have priority over events.
	modified:   mscore/data/shortcuts.xml
	modified:   mscore/musescore.cpp
	modified:   mscore/scoretab.cpp
	modified:   mscore/scoretab.h