Get rid of ext/editorialgroup

[opoudjis]

From metanorma/metanorma-iec#191

I don't think there is anything to change here with data, but we are getting rid of ext/editorialgroup and ext/approvalgroup, and replacing it with subdivisions of an additional contributor organisation. So, for the main encoding of editorial groups, as shown in ISO:

-IsoWorkgroup =
-    ## Numeric identifier of the technical committee
-    attribute number { text }?,
-    ## Type of the technical committee, used in identifying the technical committee
-    attribute type { text }?,
-    ## Non-numeric, complete identifier of the technical committee
-    attribute identifier { text }?,
-    ## Disambiguating prefix added to number to form the identifier of the technical committee,
-    ## typically indicating its type
-    attribute prefix { text }?,
-    ## Name of the technical committee
-    text

This becomes

<contributor>
  <role type="author"><description>committee</description></role>
  <organization>
    <name>{SDO name, or partner agency's}</name>
    <subdivision type="technical-committee" subtype={IsoWorkgroup/type}>
      <name>{IsoWorkgroup/type}</name>
      <identifier>{IsoWorkgroup/identifier for just the technical committee}</identifier>
      <identifier type="full">{identifier for the technical committee and its subgroups, as a single string}</identifier>
    </subdivision>
    <subdivision type="subcommittee">
      <name>{IsoWorkgroup/type}</name>
      <identifier>{IsoWorkgroup/identifier}</identifier>
    </subdivision>
    <subdivision type="workgroup">
      <name>{IsoWorkgroup/type}</name>
      <identifier>{IsoWorkgroup/identifier}</identifier>
    </subdivision>
    <abbreviation>{SDO abbreviation}</abbreviation>
  </organization>
</contributor>

Secretariats are a subdivision in a separate contributor record, with role description "secretariat". Approval groups are the same structure, with role "authorizer". In some flavours acronyms appear instead of identifiers: they are to be encoded as identifiers.