feat(user-service): Re-evaluate Spring Boot code generated by OpenAPI Generator

[tschaffter]

• Fixes Explore integrating Spring Boot code generated by OpenAPI #707
• Depends on Explore James approach to generate API server stub from OpenAPI #590
• Depends on Add google-java-format formatter #712

Changelog

• Update the OpenAPI generator.
• Refactor the user service around the code generated with the OpenAPI generator.
  • Generate code with nx openapi-generate challenge-user-service.
  • Use mustache template to customize the code generated.
• Implemented the following endpoint:
  • Get a user by id
  • List all users (paginated)
  • Register a user

  Note
  A PATCH endpoint is included but not implemented.

• Add Flyway Gradle plugin to manipulate the DB. Example:
  • ./gradlew flywayClean: delete the content of the DB.
• Enable Spring Boot app actuators.
  • http://localhost:8083/actuator
  • http://localhost:8083/actuator/health
  • http://localhost:8083/actuator/info

Note
Keeping the old code of the service for as long as it is needed.

Future work

• Update the challenge registry API spec #736
• Generate tests for the user service #735

[tschaffter]

IntelliSense cannot resolve org.sagebionetworks.challenge.util

• The library is properly installed to the local Maven cache.
• mavenLocal() is specified in build.gradle.
• The project builds successfully, so it's an IntelliSense issue.

The solution was to make a dummy edit to build.gradle, which then prompt an option to reload the (gradle) project. Once done, the library package is successfully resolved.