Navbar customization improvements (#17863)

- Add folder icon editing support
- And other navbar customization fixes/improvements.

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Co-authored-by: Copilot Autofix powered by AI <223894421+github-code-quality[bot]@users.noreply.github.com>
Co-authored-by: Devessier <baptiste@devessier.fr>
Co-authored-by: Félix Malfait <felix.malfait@gmail.com>

packages/twenty-server/src/engine/metadata-modules/object-metadata/object-metadata.service.ts

@@ -898,8 +898,9 @@ export class ObjectMetadataService extends TypeOrmQueryService<ObjectMetadataEnt
       folderId: null,
       folderUniversalIdentifier: null,
       name: null,
-      position: nextPosition,
       link: null,
+      icon: null,
+      position: nextPosition,
       workspaceId,
       applicationId: workspaceCustomApplicationId,
       applicationUniversalIdentifier: