ENH: Add inplace volumes result and schema

[mferrera]

Resolves #877

This will need refinement and discussion, but here is something to discuss.

• Suggests a module interface from _products
  • When FMU products are exported they can import the VERSION and SCHEMA to use:

  •  data:
       product:
         type: ...
         # All schema-able products have this; not every product is schema-able (e.g. roff files)
         file_schema:
           version: {fmu.dataio._products.inplace_volumes.VERSION}  # Or schema_version? Not needed?
           url: {fmu.dataio._products.inplace_volumes.SCHEMA} 

  • This should give consumers approximately what they need for data consistency guarantees
• The bad: most things are optional. Currently a valid product can look like:
  • ZONE,REGION,BULK_TOTAL,PORV_TOTAL
  • This isn't very useful -- it is a poor data contract to make (and the last two may need to be optional too?)
• This doesn't yet set-up the deployment of the schema, a way to generate them etc
  • We should have a discussion about how products and their versions are organized, relative to each-other and generally in the URL
  • This means the update_schema script in tools/ needs to be extended
  • The script that installs the schema files on the Radix app will need to be updated too

Will take documentation separately since things in here are likely to shift a bit.

[mferrera]

Now depends on #903

[tnatt]

Looks good :) Just have one comment regarding some columns that can be set to non-optional.

[mferrera]

I made #928 as well; this is probably more simply handled after iterating on #926 -- we could look at implementing a static method that returns required fields.