Set jetty UID/GID via build arguments

Feature description

Set explicit UID/GID for the jetty user via build arguments.

Use cases

• A user needs to avoid UID/GID conflict with a package that hardcodes an expected ID.

Benefits

Changing the UID or GID of the container's user is a common scenario. Exposing the IDs as build arguments makes it trivial to update the container without modifying the Dockerfile. useradd and groupadd always use the next available ID, explicitly setting the ID of the container can avoid permissions issues caused by changes to users in the base container.

Requirements

N/A

Links / references

https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#user

Definition of Done

• Feature has been implemented