fix up / make consistent themes definitions

[tomkralidis]

Follow-on of #237, as per https://github.com/opengeospatial/ogcapi-records/issues/235#issuecomment-1528834725

• cleanup of queryables examples based on core queryables
• minor editorial updates/fixes

I also refactored the themes definition into its own schema fragment/file for reuse. In theory we could use this in https://github.com/opengeospatial/ogcapi-records/blob/master/core/standard/clause_12_local_resources_catalogue.adoc#example, but the example would then show a schema reference rather than the actual inline definition (which is valuable from a spec readability perspective, but another place to update if things change i the themes definition).

Thoughts @pvretano @m-mohr?

[m-mohr]

I guess a reference would be okay and simpilfy the example. Or is there any good reason why in practice someone wouldn't use a ref and reuse existing schemas?

[tomkralidis]

@m-mohr I've updated the example to match the queryables schema as well as the various types.

As well:

I guess a reference would be okay and simpilfy the example. Or is there any good reason why in practice someone wouldn't use a ref and reuse existing schemas?

For an implementation, yes we would ref and reuse existing schemas. The question is whether to use a $ref in the example in the specification or be explicit to demonstrate the concept?

[pvretano]

01-MAY-2023: Closes #235

[m-mohr]

My review is above (https://github.com/opengeospatial/ogcapi-records/pull/246#discussion_r1181237069) and did not receive a comment yet. Otherwise looks good.

[tomkralidis]

@pvretano good catch, removed. Thanks

P.S. if/once this PR is merged, it should be "Squash and Merge"d (lots of superfluous commits).