Create a Gradle task to send release refs to Sentry

[ggalmazor]

Sentry can use refs to git commits to enhance the error reports we get when something fails. For that to work, Sentry needs to receive some information:

• a list of refs belonging to each release or
• the most recent commit of the release or
• the most recent commit of the release and the most recent commit of the previous release

Sentry docs with more info

We want to have a new Gradle task that automatizes this by getting the corresponding refs and sending them to Sentry. There are examples of how to achieve that in the Sentry docs which would have to be migrated to Groovy and that are a really good starting point.