qml: eliminate shortcut sequence binding warnings
Qt docs note that standard keys may resolve to multiple shortcuts:
Note: Given that standard keys can resolve to one shortcut on some platforms, but multiple shortcuts on other platforms, we recommend always using sequences for standard keys.
With Qt 6.8, I'm getting this warning: QML ShortcutExt: Shortcut: Only binding to one of multiple key bindings associated with 16. Use 'sequences: [ <key> ]' to bind to all of them.
Request review @chub.