Improve element name in error message for violations in DocView XMLs

[kwin]

Currently a violation in a DocView XML leads to the following message:

[WARNING] ValidationViolation: "netcentric-aem-classification: Element with name "{}test" inherits from resource '...' which is marked as 'granite:InternalArea (derived from parent content classification)'. It therefore violates the content classification!", filePath=... nodePath=.., line=5, column=82

The element name has currently the JCR Expanded Form which is not really common for XML. Therefore it should be emitted in a more human readable format.
Unfortunately the prefix used for the namespace URI is unknown to the validator, so it should just

• emit the local name only in case the namespace is empty
• emit the local name followed by the namespace URI in brackets in case the namespace is not empty

[kwin]

Unfortunately there was a bug in the fix, so I have to reopen.