Track more metrics

- About page
- Discuss page
- Help page
- Location page
- Uploader page
- Download, share and embed tabs in detail (each clickable element)
- "Use this file" closed (previous was counted as open event)

Change-Id: I1ebcb39049ad9b521968eb2024be9b86a49e5b0c
Mingle: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/851