feat(s3): support Filter rules in PutBucketNotificationConfiguration

[fguery]

Summary

PutBucketNotificationConfiguration silently drops queue/topic configurations when the
XML body contains <Filter> elements (used for key prefix/suffix filtering). The generic
XmlParser.getElementText() throws on container elements like <Filter><S3Key><FilterRule>...,
and the blanket catch (XMLStreamException ignored) swallows the error, aborting the parse
mid-stream. The notification config is stored as empty.

This PR adds a dedicated NotificationConfigurationParser that handles the full notification
schema in a single StAX pass — parsing, storing, evaluating, and round-tripping filter rules. I wasn't
able to use it to parse nested elements, and I didn't want to do too many changes there.

Type of change

• Bug fix (fix:)
• New feature (feat:)
• Breaking change (feat!: or fix!:)
• Docs / chore

AWS Compatibility

Verified with AWS CLI v2.26.1 against a local Floci dev instance.

Before: get-bucket-notification-configuration returns empty QueueConfigurations: []
when the PUT body contains <Filter> elements.

After:

• Filter rules are preserved in the round-trip (PUT → GET returns FilterRules intact)
• Prefix and suffix filters are evaluated when dispatching notifications to SQS/SNS
• Tested: uploading incoming/data.csv with filter prefix=incoming/ + suffix=.csv
  delivers exactly 1 SQS message; outgoing/data.csv and incoming/data.txt are correctly
  filtered out

Wire format follows:
https://docs.aws.amazon.com/AmazonS3/latest/API/API_PutBucketNotificationConfiguration.html

Checklist

• ./mvnw test passes locally
• New or updated integration test added
• Commit messages follow Conventional Commits

[hectorvent]

Hi @fguery,

Thanks for taking the time to contribute! We've seen your PR and will take a look soon.

To ensure this implementation stays robust, could you also open a PR in our compatibility suite at https://github.com/hectorvent/floci-compatibility-tests? This helps us validate that your changes keep working perfectly as the project evolves.

The Floci team

[fguery]

I think mtpettyp way of handling the XML parser is a bit cleaner; I can do that too -- up to you :)
The compatibility one should work either way though.

[hectorvent]

I think mtpettyp way of handling the XML parser is a bit cleaner; I can do that too -- up to you :) The compatibility one should work either way though.

I think mtpettyp way of handling the XML parser is a bit cleaner; I can do that too -- up to you :) The compatibility one should work either way though.

Yeah, sounds good. Could bring that idea to this PR? Thanks

[hectorvent]

Thanks @fguery

  PASS  S3 GetBucketNotificationConfiguration (queue filter round-trip)
  PASS  S3 GetBucketNotificationConfiguration (topic filter round-trip)