Prepare for pydanticv2

[ruscoder]

• AnyResource is now Model with resourceType
• All Resource Models (like Patient) inherit AnyResource as the first parent class. BaseModel is the second one - it restricts "extra" to forbid
• BaseModel (that is used by all models) has a validator for all fields that transform AnyResource to the particular instance (with proper validation for lists)
• primitive types have suffix Type

[ruscoder]

There's a dirty hack with primitive types - I add Type and then remove Type for unions - it needs to be re-written in a better way. But I'm afraid it will require to change our meta models to add real type and aliased type

[ruscoder]

I had to add a custom serializer and validator for BaseModel that we use for all resources to handle AnyResource validation/serialization.
Functions _validate/_serialize run for each field, it's definitely not optimized way, however, it skips to default for non AnyResource values.
I assume it might be refactored using __get_pydantic_core_schema__ with a custom schema for AnyResource/list[AnyResource] fields.

Also, there's a bit tight connection to the pydantic internals due to enumerating all fields for model_dump - but otherwise it's impossible to do it with typed kwargs.