This adds a PCP test to the IGD test server, by hardcoding in a few observed packets from
Denton's box.
Signed-off-by: julianknodt <julianknodt@gmail.com>
And use dynamic port numbers in tests, as Linux on GitHub Actions and
Windows in general have things running on these ports.
Co-Author: Julian Knodt <julianknodt@gmail.com>
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>