(kinesisanalytics-flink): add support for Flink 2.2

### Describe the feature

Amazon Kinesis Data Analytics now supports Apache Flink v2.2 ([LINK](https://aws.amazon.com/blogs/big-data/migrate-to-apache-flink-2-2-on-amazon-managed-service-for-apache-flink/))

### Use Case

Amazon Kinesis Data Analytics now supports Apache Flink v2.2 ([LINK](https://aws.amazon.com/blogs/big-data/migrate-to-apache-flink-2-2-on-amazon-managed-service-for-apache-flink/))

### Proposed Solution

- Add Flink 2.2 to Runtime type
- Update Readme to reference Flink 2.2

### Other Information

_No response_

### Acknowledgements

- [x] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### AWS CDK Library version (aws-cdk-lib)

aws-cdk-lib@2.248.0

### AWS CDK CLI version

2.1118.0 (build 2a848bc)

### Environment details (OS name and version, etc.)

macOS 26.4.1 (25E253)

Start at the kinesisanalytics-flink Runtime type and its README. Check how supported Flink versions are represented, add the requested 2.2 entry, and verify that the README references Flink 2.2.

Written by the indexing model from the issue text.