(aws-bedrock-agentcore-alpha): Gateway missing config options

### Describe the feature

Its currently not possible to set the following through CDK:
- Tracing
- Logs - gateway and identity
- Associate policy engine #37219

### Use Case

I can create the Gateway through CDK but then have to manually setup tracing, logs and policy config.

### Proposed Solution

_No response_

### Other Information

_No response_

### Acknowledgements

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

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

2.237.1

### AWS CDK CLI version

2.1115.1

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

macOS 15.7.3

Start by locating the aws-bedrock-agentcore-alpha Gateway construct and its existing configuration and tests. Trace how Gateway settings are represented and synthesized, then verify that tracing, gateway and identity logs, and policy engine association can be configured through CDK without manual setup.

Written by the indexing model from the issue text.