The health package was turning into a rando dumping ground. Make a new
Warnable type instead that callers can request an instance of, and
then Set it locally in their code without the health package being
aware of all the things that are warnable. (For plenty of things the
health package will want to know details of how Tailscale works so it
can better prioritize/suppress errors, but lots of the warnings are
pretty leaf-y and unrelated)
This just moves two of the health warnings. Can probably move more
later.
Change-Id: I51e50e46eb633f4e96ced503d3b18a1891de1452
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3f8e185003