Add injection hook for structures from a ServiceShape (#3147)

            ScopeMacroGenerator(codegenContext).render(this)

        }

        codegenDecorator.postprocessServiceGenerateAdditionalStructures(shape)

            .forEach { structureShape -> this.structureShape(structureShape) }

    }

    /**

            protocolGenerator.renderOperation(this, shape)

        }

        codegenDecorator.postprocessGenerateAdditionalStructures(shape)

        codegenDecorator.postprocessOperationGenerateAdditionalStructures(shape)

            .forEach { structureShape -> this.structureShape(structureShape) }

    }

import software.amazon.smithy.build.PluginContext

import software.amazon.smithy.model.shapes.OperationShape

import software.amazon.smithy.model.shapes.ServiceShape

import software.amazon.smithy.model.shapes.ShapeId

import software.amazon.smithy.model.shapes.StructureShape

import software.amazon.smithy.rust.codegen.core.smithy.customize.CombinedCoreCodegenDecorator

     * making the resulting crate not compile (since it will contain more than one struct with the same name).

     * Therefore, ensure that all the structure shapes returned by this method are not in the service's closure.

     */

    fun postprocessGenerateAdditionalStructures(operationShape: OperationShape): List<StructureShape> = emptyList()

    fun postprocessOperationGenerateAdditionalStructures(operationShape: OperationShape): List<StructureShape> = emptyList()

    /**

     * For each service, this hook allows decorators to return a collection of structure shapes that will additionally be generated.

     * If a structure shape is in the service's closure, note that returning it here will cause for it to be generated more than once,

     * making the resulting crate not compile (since it will contain more than one struct with the same name).

     * Therefore, ensure that all the structure shapes returned by this method are not in the service's closure.

     */

    fun postprocessServiceGenerateAdditionalStructures(serviceShape: ServiceShape): List<StructureShape> = emptyList()

    /**

     * Configuration methods that should be injected into the `${serviceName}Config` struct to allow users to configure

            decorator.postprocessValidationExceptionNotAttachedErrorMessage(accumulated)

        }

    override fun postprocessGenerateAdditionalStructures(operationShape: OperationShape): List<StructureShape> =

        orderedDecorators.flatMap { it.postprocessGenerateAdditionalStructures(operationShape) }

    override fun postprocessOperationGenerateAdditionalStructures(operationShape: OperationShape): List<StructureShape> =

        orderedDecorators.flatMap { it.postprocessOperationGenerateAdditionalStructures(operationShape) }

    override fun postprocessServiceGenerateAdditionalStructures(serviceShape: ServiceShape): List<StructureShape> =

        orderedDecorators.flatMap { it.postprocessServiceGenerateAdditionalStructures(serviceShape) }

    override fun configMethods(codegenContext: ServerCodegenContext): List<ConfigMethod> =

        orderedDecorators.flatMap { it.configMethods(codegenContext) }