Fix errors in the dialog to override a report

[varCepheid]

closes #1507
closes #1508

Makes the dialog pop up if there is an actual conflict, but not if it's just an edit.
Makes the description text in a dialog thicker so it's visible.
Adds a dialog on delete (it's not perfect but it works).

The current issues are that a) if the same user uploads a new report for the same team in the same match, it automatically overrides the old report; and b) there is no dialog to stop an accidental deletion of a report. In these changes, there are now dialogs for both of these situations.

[varCepheid]

This replaces PR #1514, which I accidentally merged handle-network-errors into. It has all the same changes I made.

[calebeby]

@varCepheid Can you add screenshots and testing instructions to this PR (in the description)?

[varCepheid]

I think they're probably in #1514 because that was the original PR. I'll move them in here when I get the chance.

[varCepheid]

I added some testing instructions in the PR description. Does that help? I checked that the changes I made did what I want them to using the deploy preview.