Use ApplicationSearch in XHProf

Summary:
Ref T12297. This slightly modernizes the XHProf UI. Not included here:

• Some of the code acts like samples have PHIDs, but they currently do not. I plan to add them in the next change.
• I've intentionally left the actual list untouched for now -- it has some old/buggy code (like flag-6 is no longer an icon) that I'll fix in a future change.

Test Plan:

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12297

Differential Revision: https://secure.phabricator.com/D17400