Keep setIcon() working for now on PHUIObjectItemView

Summary:
Ref T11501. This method was removed in D16418, but still has some callsites. I know of four:

• Config
• Settings
• Drydock main page
• Almanac main page

Since I might be missing some and it's close to the release cut, just put the method back for now until we can clean it up more properly.

Test Plan: Viewed Settings, Config, Drydock, Almanac. No more fatal on this method being missing.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11501

Differential Revision: https://secure.phabricator.com/D16420