Modernize "build plans" typeahead datasource

Summary: Ref T4420. Modernize build plans.

Test Plan:

• Used build plan typeahead in Harbormaster.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4420

Differential Revision: https://secure.phabricator.com/D9878