Fix packages base uri and introduce a console for that base uri

Summary:
The packages base uri is /packages/.
Previously, the base uri pointed to the packages search engine.
Because that prevents navigating to the publishers search engine
and the versions search engine and because the new base uri is a 404,
add a console, similar to Almanac or Nuance to link to these
endpoints. This makes the forms for publishers and versions
accessible without manually navigating there.

Test Plan:

• Clicked on the Packages application in Applications and saw a Console
• Clicked on the options in the console and saw all search engines
• Clicked on the packages crumb and got sent to the console
• Created a package and clicked on Edit Package and didn't see a 404

Reviewers: O1 Blessed Committers, aklapper

Reviewed By: O1 Blessed Committers, aklapper

Subscribers: aklapper, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25881