API to list reports submitted by a given reporter e-mail

[preaction]

The reporter e-mail address is presently the only unique ID we have for them. We should create a new API that allows reporters to view a paginated list of all the reports we've seen from them.

The API should be GET /v3/reporter/{email}. The API should return a list of the 100 most recent report summaries by that tester (this API should use CPAN::Testers::Schema::ResultSet::Stats module).

Passing the limit query parameter will change how many reports are returned. Passing the offset query parameter will skip that many reports. Through these two parameters, a user can paginate through all of their reports (if they so choose).

Passing the since query parameter should restrict the result set to only those reports submitted since the given ISO8601 date/time.