fix: Add a type deserializer to allow for JSON cloning of a JsonSchema object

[Mattias-Sehlstedt]

Change 4700208 introduced logic that involved cloning a schema with schema = cloneViaJson(schema, schema.getClass(), parameterBuilder.getObjectMapperProvider().jsonMapper());. This logic will fail for an OAS 3.1 specification, since the JsonSchema from swagger-core is not symmetric with regard to the type(s) field when doing back and forth de/serialization. See serialization configuration.

This means that types: [integer] becomes type: integer, which then cannot be deserialized back into JsonSchema.

This PR adjusts for that issue by adding a JsonSchema Mixin that forwards the type field into types.

Fixes #3314

[Mattias-Sehlstedt]

Could also potentially be handled by changing
schema = cloneViaJson(schema, schema.getClass(), parameterBuilder.getObjectMapperProvider().jsonMapper());
to
schema = cloneViaJson(schema, Schema.class, parameterBuilder.getObjectMapperProvider().jsonMapper());
given that we trust the type casting to not lose any necessary information. That is what is done for cloneViaJson for list items, and also seem to be the general pattern used within swagger-core as well.