make maven pom/metadata parsers less shit

[SpaceWalkerRS]

The old pattern was something like this

PARSER = new PomParser("https://repository.com/com/example/artifact/maven-metadata.xml");
List<MavenBuildVersion> versions = PARSER.getMeta(MavenBuildVersion::new, "com.example:artifact:");

This is a weird pattern since the URL to the maven-metadata.xml already contains details about the maven group id and artifact id, but you still have to provide the maven notation "prefix" when calling getMeta.

Also, it's not even a POM parser.

The new pattern removes redundancy and makes the different elements of the maven notation more explicit:

PARSER = new MavenMetadataParser("https://repository.com/", "com.example", "artifact");
List<MavenBuildVersion> versions = PARSER.getVersions(MavenBuildVersion::new);