Add discovery-server

[ZacBlanco]

This PR adds the discovery server from https://github.com/prestodb/discovery.

The change is split into a few commits

1. Copies all the existing code for the discovery-server module file-for-file directly into the airlift repository
2. Updates the airlift pom and discovery server pom with necessary changes to facilitate the build
   a. This intentionally changes the maven groupId from com.facebook.airlift.discovery to com.facebook.airlift to comply with the pattern that the rest of the modules in this project follow.
3. Fixes checkstyle issues where the old project did not comply
4. Changes from the modernizer plugin to comply and pass tests.

[aaneja]

LGTM. Thank you for making the modernizer fixes too!