`aio-lib-java-ims` Enhance `WorkspaceUtil` to also check in the environment variables before falling back to the files.

[nicdard]

Expected Behaviour

The WorkspaceUtil#getSystemWorkspaceBuilder method should check for properties that are set in the environment variables. The precedence should be the following:

• system properties
• environment variables
• property files

This will allow an easier way to pass overrides to the test command without the need to explicitly set those with -D option

Actual Behaviour

As of now, environment variables are not taken in consideration.

[francoisledroff]

I believe it was fixed with #216