Add a few more UIComponent flags, and ensure they are used in existing code (#7937)

* UIComponent flag: Explore rooms

To disable the room directory access on the Home space. Can be controlled with the existing ComponentVisibilityCustomisation

* Make "plus menu" respect component visibility

* UIComponent flag: Add integrations

To disable the widgets section of the room info card and addwidget slashcommand. Can be controlled with the existing ComponentVisibilityCustomisation

* Make sure invite users component applies to space rooms too

* Appease the linter

src/components/views/rooms/NewRoomIntro.tsx

@@ -135,7 +135,7 @@ const NewRoomIntro = () => {
         }
 
         let buttons;
-        if (parentSpace) {
+        if (parentSpace && shouldShowComponent(UIComponent.InviteUsers)) {
             buttons = <div className="mx_NewRoomIntro_buttons">
                 <AccessibleButton
                     className="mx_NewRoomIntro_inviteButton"