fix(mdns): answer hostname A queries after TTL (#96)

* fix(mdns): answer hostname A queries after TTL

Zeroconf answers only service queries. The A record for <alias>.local
expired from the OS cache after 120 seconds and lookups then failed.

Vendor zeroconf v1.0.0 with one change: it now answers A and AAAA
queries for the registered hostname. Fixes #95.

* fix(deps): update golang.org/x/net to v0.60.0

govulncheck reports several x/net advisories fixed in v0.60.0.
The Security Scan job fails on them.

third_party/zeroconf/LICENSE

@@ -0,0 +1,27 @@
+The MIT License (MIT)
+ 
+Copyright (c) 2016 Stefan Smarzly
+Copyright (c) 2014 Oleksandr Lobunets
+
+Note: Copyright for portions of project zeroconf.sd are held by Oleksandr 
+      Lobunets, 2014, as part of project bonjour. All other copyright for 
+      project zeroconf.sd are held by Stefan Smarzly, 2016.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+