Set up automatic superset backups

[dianabarsan]

Is your feature request related to a problem? Please describe.
Dashboards currently only exist in superset. They're crafted in the UI and the queries are autogenerated.
There is no way to write dashboards as code, and no way to do actual version control. Unfortunately.
However there is a way to export dashboards, and there is a way to import them later.
The output is a collection of yaml files that are not meant to be read by humans.

Describe the solution you'd like
Set up a process as part of cht-sync that does automatic backups for all dashboards and stores them to be available for backups.
If there is an automated way of pushing config to the instance, backups should be part of this process.

Describe alternatives you've considered
Automatic backups can be outside of cht-sync but should be ready out of the box anyway.

[dianabarsan]

This has been implemented through a reusable GitHub action: https://github.com/medic/cht-sync/tree/main/.github/actions/superset-backup