feat(core): resolve auth schemes based on the preference list

[trivikr]

Issue #, if available:
Internal JS-5811

Description of changes:
Resolves auth schemes based on the preference list

Testing is done by installing @aws-sdk/client-s3 and @smithy/core, and validating signature

$ yarn add ../aws-sdk-js-v3/clients/client-s3/aws-sdk-client-s3-3.796.0.tgz
$ yarn add ../smithy-typescript/packages/core/smithy-core-3.2.0.tgz
$ cp -R node_modules/@smithy/core/* node_modules/@aws-sdk/client-s3/node_modules/@smithy/core

Test code

import { S3 } from "@aws-sdk/client-s3";
import "@aws-sdk/signature-v4-crt";

const interceptorMiddleware = (next, context) => (args) => {
  // middleware intercept the request and return it early
  const request = args.request;
  return Promise.resolve({
    output: {
      $metadata: { attempts: 0, httpStatusCode: 200 },
      request,
      context,
    },
    response: {},
  });
};

const OutpostId = "op-01234567890123456";
const AccountId = "123456789012";
const region = "us-west-2";
const clientRegion = "us-east-1";
const credentials = { accessKeyId: "key", secretAccessKey: "secret" };

const client = new S3({
  region: clientRegion,
  credentials,
  useArnRegion: true,
  authSchemePreference: ["sigv4"],
});

client.middlewareStack.add(interceptorMiddleware, {
  step: "finalizeRequest",
  priority: "low",
});

const result = await client.putObject({
  Bucket: `arn:aws:s3-outposts:${region}:${AccountId}:outpost/${OutpostId}/accesspoint/abc-111`,
  Key: "key",
  Body: "body",
});

const headers = result.request.headers;
const authorizationHeader =
  headers["authorization"] || headers["Authorization"];

// Prints "AWS4-ECDSA-P256-SHA256" when authSchemePreference starts with "sigv4a", or is not set.
// Prints "AWS4-HMAC-SHA256" when authSchemePreference is set to "sigv4".
console.log(authorizationHeader.split(" ")[0]);

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