Design PGXN CLI UX and DevEx

[theory]

Enumerate user and developer tasks and design CLI commands to simplify or eliminate those tasks. Modify the CLI sketch as appropriate and turn it into a proper design document. (Publish as an RFC? Or addd ARDs?) Where possible, maintain compatibility with pgxn v1 and trunk.

Incomplete list of potential user tasks to design for:

• Standard Help, Version, and manual/info commands/options
• List installed extensions
• Install trunk binary package
• Build, package and install source distribution
• Unininstall a package
• Download a source distribution
• Download a trunk binary package
• Load a CREATE EXTENSION extension into a database
• Unload a CREATE EXTENSION extension from a database

Incomplete list of potential developer tasks to design for:

• Create a new extension from templates
• Increment a version in all relevant files
• Add a dependency (PGXN, core, or third-party)
• Build the extension in the current directory
• Package and install the extension
• Uninstall the extension
• Run unit/functional tests
• Run acceptance/install tests
• Release source on PGXN
• Edit metadata (PGXN, pgrx, etc.)

Done when:

• A complete design has been published, ideally with stubbed documentation, and the community has provided feedback for 3-6 weeks
• A development plan has been worked out and turned into issues in the 🛠️ CLI Milestone.