Disambiguate isEmpty()

Summary:
Fixes T10250.

Rename the one I added to hasAnyProperties() for clarity.

Test Plan:

• Viewed a project profile with content.
• Viewed a project profile with no properties.
• Viewed a workboard with tasks that had a mixture of additional projects and no additional projects.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10250

Differential Revision: https://secure.phabricator.com/D15151