Improve some typeahead matching behaviors

Summary:
Ref T8510. Sort prefix matches above non-prefix matches, so that "Ape Discovery" does not match "discovery" better than "Discovery".

Sort functions last.

Rename function internal strings so they don't get over-promoted the prefix-match rules.

Add kind of a hack to get "Project X" sorting above all the "Project X (Milestone 1)" results.

Test Plan:
Created "Ape Discovery", "Baboon Discovery", "Chimpanzee Discovery", etc.

Main project now sorts above milestones:

Prefix matches now sort above other matches:

Function results (rarely used) are now less prominent:

Better function results here:

More function results:

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T8510

Differential Revision: https://secure.phabricator.com/D16094