This is so that schemas that doesn't have schemaVersion can be generated
too

* added optional fields to filter and preset protobufs
* added field protobuf and schema
* type is optional on Preset_1 so need to be made optional on base type
  (and deleted before validation)
* schemaVersion is optional on Field_1 so need to be made optional on
  base type (and deleted before validation)
* this means utils.js/formatSchema{Key,Type} no takes optional values

Casing on a doc type shouldn't be handled specifically by the code. Nevertheless, some schemas enforce a type to a specific value (type must be i.e. 'observation', which is different from 'Observation'). This means that type "observation"  and "Observation" should have different dataTypeIds. That way we know what "type" to fill-in on returning the decoded object to be validated...
If we want the same `dataTypeId` for 'observation' and 'Observation'
(since we know we're actually talking about roughly the same type of
'document'), we could format the schemasPrefix object differently like:
Observation: `{dataTypeId: '924892', versions: {'observation': 4, 'Observation': 5}}`
or something less worse...