[PM-13177] Fix Unassigned cipher collection assignment in AC (#11419)

* [PM-13177] Add saveCollectionsWithServerAdmin to CipherService

* [PM-13177] Introduce isSingleCipherAdmin flag to AssignCollections component

apps/web/src/app/vault/org-vault/vault.component.ts

@@ -1249,6 +1249,8 @@ export class VaultComponent implements OnInit, OnDestroy {
         organizationId: this.organization?.id as OrganizationId,
         availableCollections,
         activeCollection: this.activeFilter?.selectedCollectionNode?.node,
+        isSingleCipherAdmin:
+          items.length === 1 && (this.organization?.canEditAllCiphers || items[0].isUnassigned),
       },
     });