Function createCollaborationPlugins

Copied from tiptap's collaboration extension with a few minor changes to make it work with our document api.

Changes:

• A local object is created for the plugin instance to simulate the extension's storage.
• When it needs the editor (for the contentError event), every editor currently using the doc is iterated over and sent the event.
• The normally editor level enableContentCheck option should be set here, it has no effect if passed to the extension.

See Collaboration for more info and useTestDocumentApi for an example of how to use it.