cmd/tailscale: add debug restun, rebind subcommands

In the hidden debug menu.

Change-Id: I20213f1f4e2290d36f9ff561bac0cc767400d5fd
Signed-off-by: Brad Fitzpatrick <bradfitz@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