refactor: break up vault services (#2364)

packages/services/src/Domain/VaultUser/UseCase/GetVaultUsers.ts

@@ -0,0 +1,16 @@
+import { SharedVaultUserServerHash, isErrorResponse } from '@standardnotes/responses'
+import { SharedVaultUsersServerInterface } from '@standardnotes/api'
+
+export class GetVaultUsers {
+  constructor(private vaultUsersServer: SharedVaultUsersServerInterface) {}
+
+  async execute(params: { sharedVaultUuid: string }): Promise<SharedVaultUserServerHash[] | undefined> {
+    const response = await this.vaultUsersServer.getSharedVaultUsers({ sharedVaultUuid: params.sharedVaultUuid })
+
+    if (isErrorResponse(response)) {
+      return undefined
+    }
+
+    return response.data.users
+  }
+}