This method uses `path.Join` to build the URL. Turns out with 1.24 this
started stripping consecutive "/" characters, so "http://..." in baseURL
becomes "http:/...".
Also, `c.Tailnet` is a function that returns `c.tailnet`. Using it as a
path element would encode as a pointer instead of the tailnet name.
Finally, provide a way to prevent escaping of path elements e.g. for `?`
in `acl?details=1`.
Updates #15015
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
Andrew Lytvynov