refactor: remove redundant dialogType prop from BulkMembersDialog

Remove dialogType prop and consolidate to use only isOrganizer prop.

- Remove dialogType prop from BulkMembersDialog component
- Replace all dialogType checks with isOrganizer boolean checks
- Add comments clarifying isOrganizer true/false meanings
- Remove dialog-type prop binding from MembersList component

This simplifies the component API while maintaining the same functionality.

src/components/MembersList.vue

@@ -223,7 +223,6 @@
       ref="bulkMembersDialog"
       :active-did="activeDid"
       :api-server="apiServer"
-      :dialog-type="isOrganizer ? 'admit' : 'visibility'"
       :is-organizer="isOrganizer"
       @close="closeBulkMembersDialogCallback"
     />