Disable Maniphest task list grips in panel rendering contexts

Summary:
Fixes T5467.

  - Let search engines figure out if they're rendering for a panel or not.
  - If Maniphest is rendering a panel, turn off the grips and batch selection.

Test Plan:
  - Viewed task panels (no grips).
  - Viewed non-panel query results (grips).

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T5467

Differential Revision: https://secure.phabricator.com/D9714