Expose createCompatibilityActors function and the PreviewKitNodeMsg type

[osnoser1]

Is your feature request related to a problem? Please describe.

I've finished and deployed the visual-editing and preview-kit feature in Angular; with the exposure of the channels package into @sanity/comlink, I was able to remove it from the repo; however, for implementing these features, I made an angular equivalent of useDocumentInUse.ts here document-in-use.service.ts, and I used the two new dependencies createCompatibilityActors function and the PreviewKitNodeMsg type of the @repo/visual-editing-helpers, I copied the project partially.

Describe the solution you'd like

It should be great to expose these two things through a npm package.

[rdunk]

Just wanted to provide you with an update as we've discussed this internally: we're planning on restructuring this monorepo and moving away from unpublished internal packages, so we should be able to solve this one soon. Sorry it's taken a while, thanks for your patience and the amazing work you're doing to support Angular.