Migrate AWS SDK for JavaScript v2 APIs to v3 in demos/browser

[trivikr]

Issue #:
From AWS SDK for JavaScript v2 README:

We are formalizing our plans to make the Maintenance Announcement (Phase 2) for AWS SDK for JavaScript v2 in 2023.

Description of changes:
Migrates AWS SDK for JavaScript v2 APIs to v3 in demos/browser

Testing:
CI

Checklist:

1. Have you successfully run npm run build:release locally?
   N/A

2. Do you add, modify, or delete public API definitions? If yes, has that been reviewed and approved?
   No.

3. Do you change the wire protocol, e.g. the request method? If yes, has that been reviewed and approved?
   No.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[trivikr]

Hey maintainers, looks like the CI is failing as the credentials are not present in secrets on my fork.
Feel free to cherry-pick these commits in a private branch on upstream, and post new PR.

[trivikr]

cc active contributors @dinmin-amzn @michhyun1

[trivikr]

Can someone review this PR?

[ltrung]

Hey maintainers, looks like the CI is failing as the credentials are not present in secrets on my fork. Feel free to cherry-pick these commits in a private branch on upstream, and post new PR.

The reason is GitHub environment does not allow at the workflow level and is only at the job level https://github.com/orgs/community/discussions/14417. We have waited that feature for almost 2 year now.

Due to this we currently could not be able to validate your changes against our automatic tests. Does this block you? We can copy your code to a Git clone and refer to this PR.
Thanks for contributing though.

[trivikr]

Does this block you?

No. The AWS SDK for JavaScript team is planning to announce maintenance mode in 2023, so the request will come up in future.

We can copy your code to a Git clone and refer to this PR.

That would be helpful. Feel free to cherry-pick my commits in upstream branch to post a new PR.

[ltrung]

Close this PR in favor of #2807