Change VCS info file format to JSON

[MetRonnie]

These changes close #4546

Change the workflow version control info file format from modified INI to JSON. This is still easily human readable but is much easier to parse by programs that can't use parsec (e.g. see metomi/rose#2520).

Requirements check-list

• I have read CONTRIBUTING.md and added my name as a Code Contributor.
• Contains logically grouped changes (else tidy your branch by rebase).
• Does not contain off-topic changes (use other PRs for other changes).
• Applied any dependency changes to both setup.cfg and conda-environment.yml.
• Appropriate tests are included
• Appropriate change log entry included.
• No documentation update required (updated the relevant auto-doc material)

[wxtim]

Looks good - do you want me to fix rose, or do you want to do it?

[MetRonnie]

metomi/rose#2520