DSS 6.0 migration

[bsanchezb]

Hello,

Please find modifications required for migration of your project to DSS 6.0.

The following have been done:

• eSig DSS migrated to version 6.0;
• Spring 5 application has been replaced with Spring-Boot 3;
• the structure of the project has been simplified, in favor of a single module;
• SOAP API has been removed;
• removed unused end-points for REST API;
• Dockerfile has been adapted to run spring-boot application;
• added Datadog on application launch.

Additionally, the following end-points have been added:

• liveness: accessible by http://localhost:8080/actuator/health/liveness;
• readiness: accessible by http://localhost:8080/actuator/health/readiness.

Feel free to test and let me know in case of any issues.