Add a summary of all revisions / rock sha256 published

This will make it incredibly easier to update in charms.
Similar to [this](https://github.com/canonical/mongodb-operator/actions/runs/30118530629/attempts/1#summary-89573868810)

Implementation is [here](https://github.com/canonical/mongodb-operator/actions/runs/30118530629/workflow#L119)

We could have one summary for each snap and one for each rock
The outputs do follow the same syntax

Start with the linked workflow implementation around line 119 and compare it with the referenced MongoDB Operator Actions summary. Add published summaries for each snap and each rock, including the rock SHA256, using the existing output syntax; done means all intended revisions and checksums are visible in the workflow summary.

Written by the indexing model from the issue text.