Replaces the former shell goop, which was a shell reimplementation
of a subset of version/mkversion.
Signed-off-by: David Anderson <danderson@tailscale.com>
Adds an on-demand GitHub Action that publishes the package to the npm
registry (currently under tailscale-connect, will be moved to
@tailscale/connect once we get control of the npm org).
Makes the package.json for the NPM package be dynamically generated to
have the current Tailscale client version.
Updates #5415
Signed-off-by: Mihai Parparita <mihai@tailscale.com>