Ability to add external link for requesting assistance with metadata workflow

**Is your feature request related to a problem? Please describe.**
In the current workflow process a user has to fill out the full metadata record before being able to submit an approval request.
In our environment, users don't have all the knowledge to fill out the full metadata records.

- Our records need to be bilingual and the translation is generally done by a third party
- If a WMS service is required, then our GIS team need to do some configuration work.
- Also in some cases a user may simply want some guidance on filling out the metadata which would generally go to our helpdesk.

It is currently not possible to apply a consistent process in the application. And this leads to the user doing all these task manually and it is difficult to enforce everyone to follow the same procedure.

**Describe the solution you'd like**
What is being proposed is the ability to add a link to an external BPMN application that could take care of these workflow request.

- First create an option in the setting to be able to add external support request url. I was thinking this could be in the workflow configuration however I believe it may be possible to be place elsewhere.
- Add tool for handling retrieving the url - to be used by the menu.
I was thinking the url could be in the format of "http://localhost/externalapp/?metadatauuid={metadatauuid}&metadataid={metadataid}" where, if exists, the value {metadatauuid},{metadataid} would be replace by the corresponding metadata being edited.
- Update the metadata menu so that if the support request url exists then it would add a link in the menu.

If it is desired to have the same users exists across the external tool and geonetwork then I would recommend using keycloak/SSO configuration. Otherwise, we could add a "{email}" as another parameter so that the external tool could prompt for authentication. Adding extra parameters would not be difficult.

As for the external tool, in our case we would be using a BPMN workflow application such as activiti/camunda to handle the request ensuring a consistent workflow for all the request identified above.

**Describe alternatives you've considered**
- Fork the code and add the logic - but then we need to deal with potential conflict issues when upgrading to newer versions.
- Attempt to document the process asking the users to go login to the external app to make their request. This is clunky and there are always issue with people not following the proper instructions.

**Additional context**
I believe being able to link Geonetwork to external BPMN workflow application could help enhance the functionality. Other potential usage include the publishing approval process - current Geonetwork approval process is simple - reviewer approves of rejects the record. But in some cases it can be complex requiring approvals from multiple parties i.e. translation need to approve translation, gis team needs to approve gis data, content reviewer provide general review. Attempting to put this logic into the Geonetwork software would be too complexe but allowing this to be handled by an external BPMN software seems to make more sense.

Looking for some feedback. If approved, I can begin work on applying the new enhancements.