Implement analytics on Dockerfiles

[loujaybee]

Currently, we have no visibility into how users are engaging with Dockerfiles within gitpod, i.e if the user has created a Dockerfile, and when they do that.

Note: by implementing analytics on the .gitpod.yml #6894 we might be able to get sufficient data about the Dockerfile and/or re-use the same (or similar) implementation.

DISCLAIMER: We need to be careful with this to respect users privacy. Let's investigate what changes we'll need to make to our privacy policy, or possibly implement an explicit opt-in for users to send us developer data.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.