add option for smithy codegen attribution comment in generated files

[kuhe]

This is a proposed new codegen option.

• add withAttribution: boolean default false.

    "plugins": {
        "typescript-codegen": {
            "service": "example.weather#Weather",
            "targetNamespace": "Weather",
            "package": "weather",
            "packageVersion": "0.0.1",
            "withAttribution": true,
            "packageJson": {
                "license": "Apache-2.0"
            }
        }
    }

• when true, calls to TypeScriptWriter::write will note down the caller class and allow a comment to be added at the head of generated files.

Top of Weather.ts:

// smithy-codegen: ServiceAggregatedClientGenerator
import ...

Top of WeatherClient.ts:

// smithy-codegen: AddDefaultsModeDependency, AddEventStreamDependency, ServiceBareBonesClientGenerator
import ...

• The comment has two proposed uses:
  • prevent editing of the file by hand
  • point developers reading the source file back to the responsible generator(s)

[kuhe]

line level debugging has been added to the base CodeWriter: smithy-lang/smithy#1198