Elide Components' Button label

Otherwise the label can get out of the button boundaries. Tested with
RTL text too, it's elided properly as the elipsis switches to Left on
its own.

Reviewed-by: Marco Martin

BUG: 334867

src/declarativeimports/plasmacomponents/qml/Button.qml

@@ -249,6 +249,7 @@ Item {
             color: theme.buttonTextColor
             horizontalAlignment: icon.valid ? Text.AlignLeft : Text.AlignHCenter
             verticalAlignment: Text.AlignVCenter
+            elide: Text.ElideRight
         }
     }