feat: Command classBuilder

[kuhe]

Creates a builder-style helper for concrete Command classes to reduce their boilerplate.
The builder creates Command Classes, not Command instances.

Example diff:

import { EndpointParameterInstructions, getEndpointPlugin } from "@smithy/middleware-endpoint";
import { getSerdePlugin } from "@smithy/middleware-serde";
import { HttpRequest as __HttpRequest, HttpResponse as __HttpResponse } from "@smithy/protocol-http";
import { Command as $Command } from "@smithy/smithy-client";
import {
  FinalizeHandlerArguments,
  Handler,
  HandlerExecutionContext,
  HttpHandlerOptions as __HttpHandlerOptions,
  MetadataBearer as __MetadataBearer,
  MiddlewareStack,
  SerdeContext as __SerdeContext,
  SMITHY_CONTEXT_KEY,
} from "@smithy/types";

import { ListBucketsOutput } from "../models/models_0";
import { de_ListBucketsCommand, se_ListBucketsCommand } from "../protocols/Aws_restXml";
import { S3ClientResolvedConfig, ServiceInputTypes, ServiceOutputTypes } from "../S3Client";

export class ListBucketsCommand extends $Command<
  ListBucketsCommandInput,
  ListBucketsCommandOutput,
  S3ClientResolvedConfig
> {
  public static getEndpointParameterInstructions(): EndpointParameterInstructions {
    return {
      ForcePathStyle: { type: "clientContextParams", name: "forcePathStyle" },
      UseArnRegion: { type: "clientContextParams", name: "useArnRegion" },
      DisableMultiRegionAccessPoints: { type: "clientContextParams", name: "disableMultiregionAccessPoints" },
      Accelerate: { type: "clientContextParams", name: "useAccelerateEndpoint" },
      DisableS3ExpressSessionAuth: { type: "clientContextParams", name: "disableS3ExpressSessionAuth" },
      UseGlobalEndpoint: { type: "builtInParams", name: "useGlobalEndpoint" },
      UseFIPS: { type: "builtInParams", name: "useFipsEndpoint" },
      Endpoint: { type: "builtInParams", name: "endpoint" },
      Region: { type: "builtInParams", name: "region" },
      UseDualStack: { type: "builtInParams", name: "useDualstackEndpoint" },
    };
  }
  constructor(readonly input: ListBucketsCommandInput) {
    super();
  }
  resolveMiddleware(
    clientStack: MiddlewareStack<ServiceInputTypes, ServiceOutputTypes>,
    configuration: S3ClientResolvedConfig,
    options?: __HttpHandlerOptions
  ): Handler<ListBucketsCommandInput, ListBucketsCommandOutput> {
    this.middlewareStack.use(getSerdePlugin(configuration, this.serialize, this.deserialize));
    this.middlewareStack.use(getEndpointPlugin(configuration, ListBucketsCommand.getEndpointParameterInstructions()));

    const stack = clientStack.concat(this.middlewareStack);

    const { logger } = configuration;
    const clientName = "S3Client";
    const commandName = "ListBucketsCommand";
    const handlerExecutionContext: HandlerExecutionContext = {
      logger,
      clientName,
      commandName,
      inputFilterSensitiveLog: (_: any) => _,
      outputFilterSensitiveLog: (_: any) => _,
      [SMITHY_CONTEXT_KEY]: {
        service: "AmazonS3",
        operation: "ListBuckets",
      },
    };
    const { requestHandler } = configuration;
    return stack.resolve(
      (request: FinalizeHandlerArguments<any>) =>
        requestHandler.handle(request.request as __HttpRequest, options || {}),
      handlerExecutionContext
    );
  }
  private serialize(input: ListBucketsCommandInput, context: __SerdeContext): Promise<__HttpRequest> {
    return se_ListBucketsCommand(input, context);
  }
  private deserialize(output: __HttpResponse, context: __SerdeContext): Promise<ListBucketsCommandOutput> {
    return de_ListBucketsCommand(output, context);
  }
}

becomes

import { getEndpointPlugin } from "@smithy/middleware-endpoint";
import { getSerdePlugin } from "@smithy/middleware-serde";
import { Command as $Command } from "@smithy/smithy-client";
import { MetadataBearer as __MetadataBearer } from "@smithy/types";

import { commonParams } from "../endpoint/commonParams";
import { ListBucketsOutput } from "../models/models_0";
import { de_ListBucketsCommand, se_ListBucketsCommand } from "../protocols/Aws_restXml";
import { S3ClientResolvedConfig, ServiceInputTypes, ServiceOutputTypes } from "../S3Client";

export class ListBucketsCommand extends $Command
  .classBuilder<
    ListBucketsCommandInput,
    ListBucketsCommandOutput,
    S3ClientResolvedConfig,
    ServiceInputTypes,
    ServiceOutputTypes
  >()
  .ep({
    ...commonParams,
  })
  .m(function (this: any /*Command*/, Command: any /*static*/, config: S3ClientResolvedConfig) {
    return [
      getSerdePlugin(config, this.serialize, this.deserialize),
      getEndpointPlugin(config, Command.getEndpointParameterInstructions()),
    ];
  })
  .s("AmazonS3", "ListBuckets", {})
  .n("S3Client", "ListBucketsCommand")
  .f(void 0, void 0)
  .ser(se_ListBucketsCommand)
  .de(de_ListBucketsCommand)
  .build() {}

example of potential impact:
AWS SDK EC2 client dist-js unpacked size: 4.9MB to 4.2MB