[AWS::BedrockAgentCore::Runtime] - [coverage] - Add ResourcePolicy properties

### Name of the resource

Other

### Resource name

AWS::BedrockAgentCore::Runtime

### Description

Add the resource policy to the CloudFormation resource

```
Type: AWS::BedrockAgentCore::Runtime
Properties:
# ... existing properties ...
ResourcePolicy: IAMPolicyDocument

```

### Other Details

_No response_

Start by locating the implementation or schema for AWS::BedrockAgentCore::Runtime and checking how resource policies are represented for comparable resources. Confirm where coverage tests or fixtures are defined; done means the Runtime resource accepts the ResourcePolicy IAMPolicyDocument property and the relevant coverage checks pass.

Written by the indexing model from the issue text.