Replace the positional arguments to NewAppConnector with a Config struct.
Update the existing uses. Other than the API change, there are no functional
changes in this commit.
Updates #15160
Updates #17192
Change-Id: Ibf37f021372155a4db8aaf738f4b4f2c746bf623
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>