Set up help system throughout Admin site

[taesungh]

Following from #266 and also related to reviewing applicants, it would be good to improve the help system on different pages in the Admin site by adding info links to expand the Help panel. This will require adding a new context to the Admin layout to update the content of the tools panel in the App layout in conjunction with #407.

This issue will be mainly about configuring the help panel, and the actual content can be populated later on.