Messy version of allowing resources to link to imported resources

[piemonkey]

Overview

To allow for linking from resources in a snippet to those imported, adds imported resources to those listed for creating relationships, but actually the linking only works if we create a NamedNode relationship instead of a ResourceNode. This is just a draft as we need to figure out a better way to do this.

connected issues and PRs:

Made to #1212 as that is the more finalised part of the design.

Setup

Link to plugins PR.

How to test/reproduce

See plugins PR for most details. When creating a link to an imported resource from a resource in the snippet, click 'add relationship' as normal, but create a NamedNode link with a manually entered URI.

Challenges/uncertainties

Need to figure out the right way to do this.

Checks PR readiness

• UI: works on smaller screen sizes
• UI: feedback for any loading/error states
• Check cancel/go-back flows
• Check database state correct when deleting/updating (especially regarding relationships)
• changelog
• npm lint
• no new deprecations

[elpoelma]

@piemonkey do you think this PR is still necessary? I don't think this is really a usecase right?

[piemonkey]

This definitely isn't something we need right now, but I think it's something that makes sense as there's no reason why relationships should need to have the subject in the outer document rather than the subject being inside the snippet.