Replace ant scripts with maven scripts OR make sure ant scripts properly run on all dev systems

[MartinWahnschaffe]

Maven 3.5 no longer gives the instruction to setup the M2_HOME variable, because it is related to several bugs/problems (see https://maven.apache.org/docs/3.5.0/release-notes.html). Our ant scripts rely on this and thus should better be replaced with maven goals (at least to collect server libs, etc.). In addition the maven-ant-tasks plugin for ant is retired (see http://maven.apache.org/ant-tasks/), it has been superseded by Maven Artifact Resolver Ant Tasks.

• [ ] goals to collect server libs etc.
• [ ] goals to deploy files into local server (?)
• [ ] find a convenient replacement for calling tests and installing with app

[jabrandes]

I would like to suggest an alternative: It may be worth looking at migrating the project to Gradle instead of sticking with Maven and Ant. In my point of view, its featureset combines many good features of both Maven and Ant:

• Gradle treats building as a multi-step process defined by tasks with dependencies (like Ant) instead of fixed phases with actions (like Maven), allowing flexible and more complex build processes
• Support for Multi-Project builds (like Maven)
• It includes automatic dependency resolution and download from package repositories (like Maven)
• Extensibility with plugins, which are automatically downloaded just like dependencies (like Maven)
• Versions for common plugins across subprojects can be managed in the top-level buildscript (like Maven; functionality like Maven's dependencyManagement blocks can be achieved by using io.spring.dependency-management plugin)
• It supports external files defining build properties (like Ant)

Additional advantages from using Gradle as the build system:

• You are able to run individual tasks from individual subprojects; dependency tasks are automatically resolved and executed as necessary (unlike Maven where you need to tell the reactor to include dependency builds)
• You can run subproject tasks from the respective subproject's directory directly
• Being Groovy scripts, build.gradle files can also include (or reference) arbitrary Groovy and Java code for implementation of custom functionality
• Consistency with the sormas-app project that also uses Gradle in the Maven scripts

[StefanKock]

It seems that resolver-ant-tasks could avoid the M2_HOME with overwrite mechanism for settings.xml file.