[Glitch] Rewrite actions/modal and reducers/modal with typescript

Port 38c6216082 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/actions/boosts.js

@@ -14,7 +14,10 @@ export function initBoostModal(props) {
       privacy,
     });
 
-    dispatch(openModal('BOOST', props));
+    dispatch(openModal({
+      modalType: 'BOOST',
+      modalProps: props,
+    }));
   };
 }