[Improve] [ISSUE #5628] Migrate Admin swagger from springfox to springdoc

[VampireAchao]

Fixes #5628

This PR upgrades the Swagger integration from Swagger 2 to Swagger 3 in the shenyu-examples-http-swagger2 module. The key changes include:

• Dependency Upgrades:

  • Replaced springfox-swagger-ui and springfox-swagger2 dependencies with springdoc-openapi-starter-webmvc-ui.
  • Upgraded commons-lang3.version to 3.12.0 to avoid issues with the NumberUtils.isCreatable(String) method not being found.

• Migration Adjustments:

  • All instances of Swagger 2 have been updated to Swagger 3.
  • Annotations have been modified as per the migration guidelines provided in the Springdoc documentation.

• Verification:

  • Ensured that the API documentation functionality remains correct and operational after the upgrade.

Make sure that:

• [x] You have read the contribution guidelines.
• [x] You submit test cases (unit or integration tests) that back your changes.
• [x] Your local test passed ./mvnw clean install -Dmaven.javadoc.skip=true.