Add protocol implementations, operation shape generation, type registry

[haydenbaker]

Very WIP, putting up just for visibillity

Several TODOs, organization still TBD

Example operation type:

@dataclass(kw_only=True, frozen=True)
class GetCity(APIOperation["GetCityInput", "GetCityOutput"]):
    input = GetCityInput
    output = GetCityOutput
    schema = _SCHEMA_GET_CITY
    input_schema = _SCHEMA_GET_CITY_INPUT
    output_schema = _SCHEMA_GET_CITY_OUTPUT
    error_registry = TypeRegistry(
        {
            ShapeID("example.weather#NoSuchResource"): NoSuchResource,
        }
    )
    effective_auth_schemes = [ShapeID("smithy.api#noAuth")]

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