feat(stepfunctions-tasks): add architecture support to EvaluateExpression (#35468)

### Issue # (if applicable)

Closes #34974

### Reason for this change

Adding an optional architecture parameter to EvaluateExpressionProps which allows users to specify their desired architecture when using the EvaluateExpression construct. This enables support for ARM64 Lambda functions, which can provide better price-performance for certain workloads.

### Description of changes

- Add optional architecture parameter to EvaluateExpressionProps
- Support ARM_64 and X86_64 Lambda architectures  
- Add comprehensive unit and integration tests
- Update documentation with usage examples
- Pass architecture parameter through to EvalNodejsSingletonFunction

### Describe any new or updated permissions being added

No new or updated IAM permissions are required. The existing Lambda invoke permissions remain unchanged as the architecture parameter only affects the Lambda function configuration, not the required permissions.

### Description of how you validated changes

- Added unit tests covering both ARM_64 and X86_64 architectures
- Created integration tests for ARM64, X86_64, and default (no value specified) architecture scenarios
- Verified CloudFormation templates generate correct architecture specifications
- Tested that existing functionality remains unchanged when architecture is not specified (defaults to X86_64)

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: claypack