Changes ported from https://github.com/awsdocs/aws-doc-sdk-examples/p…

[brmur]

Copied from #1029 (described below)
(also did clean up of code and added tests)

#1029 PR description:
As below are all the changes to the Lambda example:

Add flattened zip folder in to the repo, making it easier to contribute.
Update all the scripts, front-end code and back-end lambda function code into V3 flavor
Use webpack for frontend SDK code because V3 no longer provide browser SDK from CDN
Use webpack for bundling Lambda function because lambda native runtime doesn't provide modularized V3 SDK like V2 does. This means you cannot just type const AWS = require('aws-sdk') to import the SDK
TODO Other than these change, the paired doc needs to be updated as well.
The original repo only comes with a .zip archive which makes it very hard to show the code change.
So I deflated the archive in first commit. So if you see the second commit(d2af238), it contains all the code change migrating from V2 to V3

• The submitter has added the default copyright notice to all files.

• The submitter has added unit tests for all code paths, run all of them, and they all pass.

• The submitter has run a linter on the code, and all of the submitter's team's minimum rules pass.

• The submitter has added the team's minimum usage documentation to the code.

• The submitter has had their Editor edit all comments and strings, and the submitter has incorporated any and all resulting edits.

• The submitter has added all of the submitter's team's related API reporting metadata.

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

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

[beckandros]

Edits for descriptions, comment strings.

[brmur]

ready to merge.