fix: add S3Client reflection hint

Motivation and Context

Fixes: https://github.com/aws/aws-sdk-java-v2/issues/5530

Modifications

Added reflection-config.json to software.amazon.awssdk:s3

Testing

Build a GraalVM native image with AWS SDK V2 for Java and AWS CRT Java and run it. The native image will fail with the error described in the issue. If you add the reflect-config.json with the information provided in the PR it is fixed.

Screenshots (if appropriate)

Types of changes

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)

Checklist

[x] I have read the CONTRIBUTING document
[x] Local run of mvn install succeeds
[x] My code follows the code style of this project
[ ] My change requires a change to the Javadoc documentation
[ ] I have updated the Javadoc documentation accordingly
[x] I have added tests to cover my changes
[x] All new and existing tests passed
[x] I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
[ ] My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

[x] I confirm that this pull request can be released under the Apache 2 license

aws / aws-sdk-java-v2

fix: add S3Client reflection hint #5531