Update React Version in Sample Apps

[Saipriya-1144]

Updated from 19.0.0 to 19.2.1 to address security vulnerabilities

• For create-react-app-sample, Regenerated app using latest create react app guidelines (https://create-react-app.dev/docs/getting-started/) due to compatibility issues.
• For DotnetcoreReact App, migrated from react-scripts to Vite to resolve security vulnerabilities

Testing: All these sample apps ran successfully in local environment

• The purpose of this PR is explained in this message or in an issue. If an issue please include a reference as #<issue_number>.
• Tests are included and/or updated for code changes.
• Proper license headers are included in each file.