feat: Create sample for routeoptimization

[bshi]

Description

Note: Before submitting a pull request, please open an issue for discussion if you are not associated with Google.

Checklist

• [X] I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• [X] README is updated to include all relevant information
• [ ] Tests pass: nox -s py-3.9 (see Test Environment Setup)
• [ ] Lint pass: nox -s lint (see Test Environment Setup)
• [X] These samples need a new API enabled in testing projects to pass (let us know which ones) routeoptimization.googleapis.com
• [ ] These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• [x] This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• [x] This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• [x] Please merge this PR for me once it is approved