Add i/o to feature metadata

[aksiome]

Suggestion or Inquiry

This is quite a long shot, but the idea is to leverage these metadata to create mcdoc files, which would improve their use with Spyglass. Additionally, this could help automatically generate documentation for features, significantly simplifying the documentation process.

[theogiraudet]

Do you have an example of which aid we can obtain from Spyglass by providing it with such mcdoc files?

[aksiome]

We can have autocompletion mainly for storages. I'm not sure if it's possible for macros at the moment, but if not, it might be in the future. Also, when installing Bookshelf through pip, the modules aren't loaded by Spyglass, so this could be a way to provide autocompletion for functions in that case.

[aksiome]

I think we should wait for IMP Doc v2, which will support defining impdoc files directly. Moving this out of the milestone for now.