Change version/draft to version/identifier

[opoudjis]

We want to change the name of version/draft to version/identifier, because draft is misleading: the version being identified may be published, and not just a draft. See discussion in metanorma/metanorma-bipm#453

@andrew2net @ronaldtse Please confirm that this will not raise any difficulty. If it doesn't,

• @opoudjis will update the grammar to use the new tag name
• @andrew2net will change the relaton stack to use the new tag name
• @opoudjis will update Metanorma (in Rename draft version into actual version, as BIPM documents have Edition and Version within Edition metanorma/metanorma-bipm#453) to use the new tag name

[andrew2net]

@opoudjis Relaton will need to be updated to handle the change

[opoudjis]

Change:

• version/draft will change to just version, and will take the existing value of either version/draft or version/revdate; if both are present, it will take the value {{version/draft}} ({{veresion/revdate}})
• version/revdate was properly intended for identification of the version; the date when the revision happens, if it is to be used as a date, resides in date[@type = 'updated']

Please update me as to when the Lutaml-Model port is complete, so I can make the needed grammar change as a precursor to this.

[opoudjis]

This remains a blocker, @ronaldtse @andrew2net