Separate MessageDelegateContextMenu to its own base component

This is the first step in separation, so we can focus more on the
actions in this menu, and it's not tangled up in how the context menu is
shown and displayed.

src/CMakeLists.txt

@@ -321,6 +321,8 @@ qt_add_qml_module(neochat URI org.kde.neochat NO_PLUGIN
         qml/LoadComponent.qml
         qml/RecommendedSpaceDialog.qml
         qml/RoomTreeSection.qml
+        qml/DelegateContextMenu.qml
+        qml/ShareDialog.qml
     RESOURCES
         qml/confetti.png
         qml/glowdot.png