Remove references to MatrixClient.crypto (#28204)

* Remove `VerificationExplorer`

* Remove `remakeolm` slash command

* Remove call to `crypto.cancelAndResendAllOutgoingKeyRequests`

* Remove crypto mock in `LoginWithQR-test.tsx`

* Remove `StopGadWidgetDriver.sendToDevice`

* Remove remaining mock

test/unit-tests/components/views/settings/devices/LoginWithQR-test.tsx

@@ -51,7 +51,6 @@ function makeClient() {
         },
         getClientWellKnown: jest.fn().mockReturnValue({}),
         getCrypto: jest.fn().mockReturnValue({}),
-        crypto: {},
     } as unknown as MatrixClient);
 }
 
@@ -194,7 +193,6 @@ describe("<LoginWithQR />", () => {
         });
 
         test("approve - no crypto", async () => {
-            (client as any).crypto = undefined;
             (client as any).getCrypto = () => undefined;
             const onFinished = jest.fn();
             render(getComponent({ client, onFinished }));