Read 'phabricator.uri' and 'default' out of more config sources
Summary: We have old/inconsistent code for reading these. Instead, read from sources in a modern way.
Test Plan:
- Removed "default" and "phabricator.uri" from user/local/project config.
- Set "default" in "/etc/arcconfig".
- Ran arc tasks and got a "connect to Phabricator" message.
Reviewers: btrahan, davedash
Reviewed By: davedash
Subscribers: davedash, epriestley
Differential Revision: https://secure.phabricator.com/D9105