Add support for pnpm-workspace.yaml

[adamalfredsson]

Thanks for this extension! I'd like to display updates in pnpm workspace catalogs. There is an issue #43 which is somewhat related. Thought I could take a stab at it:

I'm happy to continue working on this PR based off your feedback.

TODO:

• [ ] Seems like changelog quick action isn't showing
• [ ] Update global action "package.json" references
• [ ] Add documentation

[pgsandstrom]

Sorry for the delay. I'll get around to a proper code review eventually, but I'm a bit overwhelmed by work currently. I've never used pnpm-workspaces myself, so I'll have to read up on the subject before I take a stance on it.

[trydofor]

https://github.com/antfu/vscode-pnpm-catalog-lens/issues/5