Editor: not all pattern restrictions of the metadata schema are properly reflected in the editor

[cspurk]

The xs:pattern restrictions of the metadata schema for at least httpURI and emailAddress (cf. https://github.com/metashare/META-SHARE/blob/6b4e179accc4b64d86ad9e2bbc5605231a224f48/misc/schema/v3.0/META-SHARE-SimpleTypes.xsd#L13-26) are not properly reflected in the editor. For example, the editor allows newline characters at the end of corresponding values.

[cspurk]

Repoening this issue as it is actually only partly fixed: it is still the case that our Django validator for httpURI values does not make sure that corresponding values match the xs:anyURI type’s value space.

It may make sense to wait with fixing this until #640 is fixed because currently our httpURI in the schema is not very elaborate either.