chore(middleware-flexible-checksums): use RequestChecksumCalculation and ResponseChecksumValidation without interceptor middleware

[trivikr]

Issue

Internal JS-5396

Description

Uses values in RequestChecksumCalculation and ResponseChecksumValidation to decide flexible checksums algorithm.
Also deprecates MD5, and sets CRC32 as default.

Testing

Unit testing

Also, verified that checksums are computed by default

import { S3 } from "../aws-sdk-js-v3/clients/client-s3/dist-cjs/index.js";
import { NodeHttpHandler } from "@smithy/node-http-handler";

class CustomHandler extends NodeHttpHandler {
  constructor() {
    super();
  }

  async handle(request, options) {
    for (const [header, value] of Object.entries(request.headers)) {
      if (header.startsWith("x-amz-checksum-")) {
        console.log(`request['${header}']: '${value}'`);
      }
    }
    const response = await super.handle(request, options);
    for (const [header, value] of Object.entries(response.response.headers)) {
      if (header.startsWith("x-amz-checksum-")) {
        console.log(`response['${header}']: '${value}'`);
      }
    }
    return response;
  }
}

// WHEN_SUPPORTED is default.
const client = new S3({
  requestHandler: new CustomHandler(),
});

console.log("Put Object");
await client.putObject({
  Bucket: "test-flexible-checksums-v2",
  Key: "hello-world.txt",
  Body: "Hello World",
});

console.log("\nGet Object");
await client.getObject({
  Bucket: "test-flexible-checksums-v2",
  Key: "hello-world.txt",
});

Output

Put Object
request['x-amz-checksum-crc32']: 'ShexVg=='
response['x-amz-checksum-crc32']: 'ShexVg=='

Get Object
request['x-amz-checksum-mode']: 'ENABLED'
request['x-amz-checksum-crc32']: 'AAAAAA=='
response['x-amz-checksum-crc32']: 'ShexVg=='

An integration test will be added in S3 as a follow-up.

---

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[trivikr]

Converting to draft, since this solution consumes the steam during validation

import { S3 } from "../aws-sdk-js-v3/clients/client-s3/dist-cjs/index.js";

// WHEN_SUPPORTED is default.
const client = new S3({
  // responseChecksumValidation: "WHEN_REQUIRED",
});

const { Body } = await client.getObject({
  Bucket: "test-flexible-checksums-v2",
  Key: "hello-world.txt",
  // ChecksumMode: "ENABLED",
});

// Prints nothing in current setup.
// Prints "Hello World" when responseChecksumValidation is "WHEN_REQUIRED"
// Prints nothing when responseChecksumValidation is "WHEN_REQUIRED" and ChecksumMode is "ENABLED"
console.log(await Body.transformToString());

An alternative is being tested in #6492

[trivikr]

Superceded by #6492