Move applicant summary charts

[waalbert]

The first thing admin users see on the admin portal is a pie chart of the summary of applicants' statuses at /admin/dashboard. Due to adding more applicant pages for mentors and volunteers, it would make more sense to move this pie chart to /admin/applicants and create more pie charts for mentors and volunteers while having links on each chart title to their respective applicant pages (#574). The existing application summary charts at /admin/applicants can be moved to /admin/dashboard.

[taesungh]

I feel like the charts showing daily counts are more specific to the application cycle whereas the donut charts for statuses are relevant even beyond the time applications are received and reviewed (i.e. waiver signed, confirmed, attending, void). In my mind, the three charts for #574 would make more sense being visible right on the dashboard with the daily charts remaining within the Applicants page.

Perhaps omitting the rejected and waitlisted portions could also help make it fit better?

[waalbert]

I was thinking of a way to logically link the daily charts on the Applicants page to each of the specific applicant pages, but I guess there doesn't really need to be links because the specific applicant pages are on the sidebar.