wip: dbus activation & single instance support

refactor: activation action with new trait for subcommand and args

refactor: libcosmic can handle sending the activation request

cleanup

src/app/core.rs

@@ -62,6 +62,8 @@ pub struct Core {
 
     #[cfg(feature = "applet")]
     pub applet: crate::applet::Context,
+
+    pub single_instance: bool,
 }
 
 impl Default for Core {
@@ -104,6 +106,7 @@ impl Default for Core {
             },
             #[cfg(feature = "applet")]
             applet: crate::applet::Context::default(),
+            single_instance: false,
         }
     }
 }