Maven files are parsed multiple times with Maven

[fabapp2]

The behaviours of

• RewriteProjectParserIntegrationTest.shouldPublishParsingEvents
• RewriteProjectParserTest.parseComplexMavenReactorProject2

differ from IntelliJ when running in Maven. Tests currently @Disabled.

What needs to be done

• Only relevant pom files must be parsed
• All files should be parsed only once
• Every resource should exist only once in AST

[fabapp2]

fixed in: #904