CLI UX improvement: `dsc extension list`

[michaeltlombardi]

Summary of the new feature / enhancement

As a user, I want to quickly filter for available extensions by their metadata,
so that I can search for relevant extensions when I don't know their name
without having to retrieve all extensions and filter with a pipeline.

Proposed technical implementation details (optional)

We could add support for the following filtering options:

• --version, accepting a semantic version requirement
• --capabilities, accepting a literal capability. Users can specify multiple times to create and AND filter, so dsc extension list --capability discover --capability secret would only return extensions with both the discover and secret capabilities.
• --description, accepting a string with wildcards that matches on the text of that field.
• --author, accepting a string with wildcards that matches on the text of that field.