message: Convert /verify to checkDeviceTrust
  Also de-promiseify the code a bit
diff: @@ -780,15 +780,14 @@ export const CommandMap = {
  const deviceId = matches[2];
  const fingerprint = matches[3];
  - return success(
  - // Promise.resolve to handle transition from static result to promise; can be removed
  - // in future
  - Promise.resolve(cli.getStoredDevice(userId, deviceId)).then((device) => {
  + return success((async () => {
  + const device = await cli.getStoredDevice(userId, deviceId);
  if (!device) {
  throw new Error(_t('Unknown (user, device) pair:') + ` (${userId}, ${deviceId})`);
  }
  + const deviceTrust = await cli.checkDeviceTrust(userId, deviceId);
  - if (device.isVerified()) {
  + if (deviceTrust.isVerified()) {
  if (device.getFingerprint() === fingerprint) {
  throw new Error(_t('Device already verified!'));
  } else {
  @@ -810,8 +809,8 @@ export const CommandMap = {
  }));
  }
  - return cli.setDeviceVerified(userId, deviceId, true);
  - }).then(() => {
  + await cli.setDeviceVerified(userId, deviceId, true);
  +
  // Tell the user we verified everything
  const InfoDialog = sdk.getComponent('dialogs.InfoDialog');
  Modal.createTrackedDialog('Slash Commands', 'Verified key', InfoDialog, {
  @@ -826,8 +825,7 @@ export const CommandMap = {
  </p>
  </div>,
  });
  - }),
  - );
  + })());
  }
  }
  return reject(this.getUsage());
  