feat: allow s3 cors options to be configured

[lukebellamy053]

Problem

Currently there is no nice way of setting the CORS configuration of an S3 bucket without using CloudFormation templates and escape hatches

The core problem here is that the default CORS options do not expose amzn-meta-* headers which means meta data is useless to a frontend consumer

Changes

Added the option to define a CORSRule array at the defineStorage level, if present, this will be used over the default

Validation

Added a unit test that validates the CORS settings are applied to the CDK template when the option is set
There is already a unit test that validates the default CORS options are used when the setting is not provided

Checklist

• If this PR includes a functional change to the runtime behavior of the code, I have added or updated automated test coverage for this change.
• If this PR requires a change to the Project Architecture README, I have included that update in this PR.
• If this PR requires a docs update, I have linked to that docs PR above.
• If this PR modifies E2E tests, makes changes to resource provisioning, or makes SDK calls, I have run the PR checks with the run-e2e label set.

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

[changeset-bot]

🦋 Changeset detected

Latest commit: d5e3ff0

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@aws-amplify/backend-storage	Minor

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