Add DataCite-accepted identifiers

Here are the identifiers that could be added to the `identifier` schema in InvenioRDM (https://github.com/inveniosoftware/rfcs/pull/11) mostly because DataCite accepts them. It would be nice to have them supported in the module.

- [ ] `igsn` (International Geo Sample Number) Their syntax is described here: http://igsn.github.io/syntax/ .
- [ ] `lissn` perhaps just redirect to `issn`
- [ ] `w3id` . [Syntax](https://w3id.org/) seems very loose
- [ ] `upc` . Perhaps superseded by `ean13` anyway
- [ ] `eissn` Perhaps just redirect to `issn`
- [ ] `bibcode` [Syntax](https://en.wikipedia.org/wiki/Bibcode)
- [x] `ror` Research Organization Registry: https://ror.org/facts/
- [x] Software Heritage Identifier: https://docs.softwareheritage.org/devel/swh-model/persistent-identifiers.html