Remove optional step for DOI creation

[J4bbi]

• Issue: Give all records a Datacite DOI #130

This PR replaces the PIDField that takes care of getting a DOI for a record (as a side note, the current InvenioRDM version being developed, version 13, has refactored the PIDField component and associated components considerably).

Default behaviour

The default behaviour for DOIs is to allow for DOIs through Datacite or external (unmanaged) DOIs - a free text field.

The external option is selected by default. Selecting the No radio button disables the input text field and displays a button to "Get a DOI". Clicking the button will submit the submission form with a RESERVE_PID action context.

When the form is submitted and internal PID is created, for example d8vn9-t2z67, but the record remains in draft form.
Another request is made to the pids endpoint: /d8vn9-t2z67/draft/pids/doi?expand=1 and the DOI has been reserved. As far as I understand, by reserving the DOI, metadata will be uploaded to Datacite but the DOI won't be published.

New behaviour

The notion of an externally managed DOI is removed from config (see here) and the hard-coded preset default values for the form are overwritten (see here).

The user can still get and discard a DOI, regardless two DOIs will be created on publication (as DOIs are set as being mandatory in config). This form element merely allows the user to reserve a DOI and use it's value.

Improvements

This PR can be enhanced by improving label/help text and possibly adding a copy value button. Also, adding documentation about this customisation.

I'm not sure how to approach skipping the button altogether. Submitting the form on condition on load doesn't seem straight forward and neither does overwriting the publish button, moreover, the user would not be apply to see the DOI before publication then.

Developer Checklist

Developers should review and confirm each of these items before requesting review

• Code meets acceptance criteria from issue
• Unit tests are written and all pass
• User Test Scripts (if required) are written and have been run through
• Code documentation and related non-code documentation has all been updated

Reviewer Checklist

Reviewers should review and confirm each of these items before approval
If there are multiple reviewers, this section can be duplicated for each reviewer

• Code meets acceptance criteria from issue
• Unit tests are written and all pass
• User Test Scripts (if required) are written and have been run through
• Code documentation and related non-code documentation has all been updated
• Migation has been created and tested

Testing

List user test scripts that need to be run

List any non-unit test scripts that need to be run

[cc-a]

Thanks @J4bbi. Looks good.

I'm going to create a separate issue for documenting this that can be actioned once #147 is merged.