Implement ferret engine in typeahead datasource query for repos

Summary:
This broadens the typeahead datasource search for repos. Before this patch a repository named "Alligator Simulator" would not be found with the search string "simu...". This is patched with the ferret engine search and indexing features.

See T15583

Test Plan: Create repositories with titles with 2 or more words. Search for these repos with the global typeahead search. The search term should begin with the second/third/n-th word of the repo title.

Reviewers: O1 Blessed Committers, avivey

Reviewed By: O1 Blessed Committers, avivey

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

Maniphest Tasks: T15583

Differential Revision: https://we.phorge.it/D25430