With --ask it might call back to nmcli's agent, causing a deadlock
while the client is waiting for the response. Let's give the client
a chance to service the agent requests while waiting:

  $ nmcli --ask --show-secrets c show 'Oracle HQ'
  <hang>

This is probably still rather suboptimal and inefficient, since we
still serialize the calls and block on response. However, if we submit
multiple calls to GetSecrets, the daemon would start authorizing the
first one and fail the other ones immediately before the authorization
succeeds.

This could perhaps be addressed in the daemon, but let's settle for a
fix that's compatible with the current daemon for now.