Build model containing multi-module relationships from Maven projects.

[mezarin]

Extract parent, child, and other needed information from build related metatype file (i.e. pom.xml).
See related LTI issue: OpenLiberty/liberty-tools-intellij#1270
For the time being focus on pom.xml parsing and other available information to build the model. Building effective pom.xml counterparts are noticeably very expensive particularly when dealing with large projects.