appc,feature/conn25: conn25: send address assignments to connector

After we intercept a DNS response and assign magic and transit addresses
we must communicate the assignment to our connector so that it can
direct traffic when it arrives.

Use the recently added peerapi endpoint to send the addresses.

Updates tailscale/corp#34258
Signed-off-by: Fran Bull <fran@tailscale.com>

tsnet/depaware.txt

@@ -235,7 +235,7 @@ tailscale.com/tsnet dependencies: (generated by github.com/tailscale/depaware)
         tailscale.com/ipn                                            from tailscale.com/client/local+
         tailscale.com/ipn/conffile                                   from tailscale.com/ipn/ipnlocal+
      💣 tailscale.com/ipn/ipnauth                                    from tailscale.com/ipn/ipnext+
-        tailscale.com/ipn/ipnext                                     from tailscale.com/ipn/ipnlocal
+        tailscale.com/ipn/ipnext                                     from tailscale.com/ipn/ipnlocal+
         tailscale.com/ipn/ipnlocal                                   from tailscale.com/ipn/localapi+
         tailscale.com/ipn/ipnlocal/netmapcache                       from tailscale.com/ipn/ipnlocal
         tailscale.com/ipn/ipnstate                                   from tailscale.com/client/local+