Custom command logic fails if not suitable base image is used

[Mingela]

gradle-sora-plugin/src/main/groovy/jp/co/soramitsu/devops/docker/DockerPlugin.groovy

Line 218 in 1ca74ec

t.runCommand "groupadd -r appuser && useradd -r -g appuser appuser"

Here we have groupadd hardcoded which is not available in alpine images, like eclipse-temurin:17-jre-alpine

I suggest to introduce another variable with image 'mode' (e.g. BusyBox, Ubuntu, Debian etc) to indicate what syntax should be used and use the suitable command instead