Use PassphraseFields in ExportE2eKeysDialog to enforce minimum passphrase complexity (#11222)

* Use PassphraseFields in ExportE2eKeysDialog to enforce minimum passphrase complexity

* Tweak copy

* Iterate

* Add tests

* Improve variable naming

* Improve coverage

test/test-utils/test-utils.ts

@@ -241,6 +241,7 @@ export function createTestClient(): MatrixClient {
         joinRoom: jest.fn(),
         getSyncStateData: jest.fn(),
         getDehydratedDevice: jest.fn(),
+        exportRoomKeys: jest.fn(),
     } as unknown as MatrixClient;
 
     client.reEmitter = new ReEmitter(client);