Add CLI command to list projects

[joezuntz]

This adds a new sub-command of dregs show, dregs show projects which lists all projects in the DB. I have occasionally had trouble remembering what I named a project and this is a quick helper to remind me!

(written with copilot).

[Copilot]

Pull request overview

Adds a new dregs show projects CLI subcommand to list “project” owners recorded in the registry, which helps users discover/recall project names currently present in the DB.

Changes:

• Add a show projects subcommand to the CLI parser and dispatch.
• Implement Query.get_project_list() to retrieve distinct project owners from datasets.
• Add an end-to-end CLI test covering show projects output and filtering.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
tests/end_to_end_tests/test_cli.py	Adds an end-to-end test verifying show projects lists project owners and excludes non-project owners.
src/dataregistry/query.py	Introduces get_project_list() to query and return unique project owners.
src/dataregistry_cli/show.py	Adds projects handling to dregs_show to print the project list.
src/dataregistry_cli/cli.py	Registers the show projects subcommand and wires it into main() dispatch.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.