Update firebase data storage pattern

[aliirz]

We need to come with a structure that tells us what websites were offline etc.

[mbyx]

We can use the date that the performance check was done on as the collection name, which holds all the documents, and the documents would be named either by the url itself or it's static IP.

The documents would contain the full url (if needed), the performance score, and other metrics such as whether the check failed or not.

To make sure that we don't have to change this structure multiple times it would be best to first decide what metrics are essential to be generated from the reports in #6.