cmd/tailscale: improve ping error message when logged out

Refactor out the pretty status printing code from status, use it in ping.

Fixes #3549

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f