Separate add resource modal domain

[RNR1]

Separate add resource modal domain

Change Summary

Separated the "Add resource" domain:

• The AddResourceModal is now ContributeModal, that, depending on future conditions, will either branch out to adding a resource or editing a resource
• Removed the "Add" domain from the resource forms, each owns both edit or add functionality (edit is not yet connected)
• A new AddResourceForm component is rendered by the ContributeModal and owns the add mutations and rendering the correct resource form

Change Reason

We are implementing the resource revisions feature