Add a flag to open --data-view with only read credentials (-r|--read-only)

`abc 0.4.0`, a read-only credentials view would make sharing the URL safer.

##### Checks

- [x] I have mentioned my `abc` version in the issue, if applicable.
- [x] This issue is not a duplicate.
- [x] This issue has a description.

Start by locating the CLI entry point and flag handling for --data-view, then trace how credentials are passed when the view opens. The change is done when -r/--read-only is accepted and the resulting shared URL uses only read credentials; verify the existing data-view flow still works.

Written by the indexing model from the issue text.