Add ability to edit a discovery dataset's details

### StatGPT Admin Frontend version

_(please fill in)_

### What is the problem this feature will solve?

If a discovery dataset record has an error or needs a small correction (e.g. a typo in its name or description), there's currently no way to fix it from the Discovery Datasets page. The only option is to re-upload the whole file.

### What is the feature you are proposing to solve the problem?

Add an "Edit" action to each dataset row on the Discovery Datasets page that opens a form pre-filled with the dataset's current details, lets the admin update the fields, and saves the changes.

### What alternatives have you considered?

_(none)_

Start at the Discovery Datasets page and trace how dataset rows currently display details and handle uploads or saves. Add the requested Edit action and pre-filled form for correcting dataset details, then verify that updated values are saved and shown in the row.

Written by the indexing model from the issue text.