492: Update admin tab UI

[carrollsa]

Closes #492

Note: "This may take a few minutes" message only appears on the call to make the match, as it is significantly longer than the others.

Change Summary

• Cleans up Admin UI
• Adds call to /api/get_last_runs and displays last execution times for each of the upload types
• Refactors components in Admin.js to separate components
• Removes moment in favor of moment-timezone so we can display times in Eastern time as opposed to the local container's time
• Removes some unused code from Admin.js
• Adds message that match may take a couple of minute
• Adds useAlert hook and refactors current alert banner usage.