[security-getting-started.adoc] Finish the Tutorial: Secure a Quarkus application by using Basic authentication with JPA

This task is done when:

• A new diataxis Tutorial is created that demonstrates how you can Secure a Quarkus application by using Basic authentication with JPA.
• Existing content identifiedsecurity-getting-started.adoc & security-builtin-authentication.adoc is moved into this tutorial topic.
• Minimal style effort.
• Xrefs and links are updated accordingly throughout the other topics in the repo. THIS IS THE BIT FOR SPRINT 2
• All is SME approved and merged to main.

Original state before poc: https://quarkus.io/version/2.7/guides/#security