Make API more consistent

[rcannood]

Description of feature

When I make a call to Get schema, I get something like this:

core:
  run:
    fields_metadata:
      id:
        type: BigAutoField
        through: ~
        field_name: id
        model_name: run
        column_name: id
        schema_name: core
        is_link_table: no
        relation_type: ~
        related_field_name: ~
        related_model_name: ~
        related_schema_name: ~
      uid:
        type: CharField
        through: ~
        field_name: uid
        model_name: run
        column_name: uid
        schema_name: core
        is_link_table: no
        relation_type: ~
        related_field_name: ~
        related_model_name: ~
        related_schema_name: ~
      parent:
        type: ForeignKey
        through:
          left_key: parent_id
          right_key: id
          link_table_name: ~
        field_name: parent
        model_name: run
        column_name: parent_id
        schema_name: core
        is_link_table: no
        relation_type: many-to-one
        related_field_name: children
        related_model_name: run
        related_schema_name: core
...

Could we make the naming system of "modules", "models", and "fields" consistent across what I'm being told to use, the API and the schema?

• I was told by Alex that core, bionty, ... are modules, Artifact, Run, ... are registries, and that a record in a registry as fields.
• In the API, all instances of {model_name} should be renamed to {registry_name}. For example: POST /instances/{instance_id}/modules/{module_name}/{model_name}/{id_or_uid}
• In a registry's fields_metadata, the following keys should be renamed:
  • model_name → registry_name
  • schema_name → module_name
  • related_model_name → related_registry_name
  • related_schema_name → related_module_name