### Issue # (if applicable)

Closes aws#30681 .

### Reason for this change
In [aws-location-alpha](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-location-alpha-readme.html), [route calculator](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_location.CfnRouteCalculator.html) has not been supported yet.



### Description of changes
Add `RouteCalculator` class.



### Description of how you validated changes
Add unit tests and integ tests.


### 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*