eclipsecs-sevntu-plugin is broken since eclipse-cs 8.36.1

[rnveach]

Identified at sevntu-checkstyle/sevntu.checkstyle#857 ,

It seems eclipsecs-sevntu-plugin's old meta data XML files no longer work, even though eclipse-cs still has code to support it. This is causing none of Sevntu's checks to appear in the Checkstyle Configuration dialog.

eclipse-cs/net.sf.eclipsecs.core/src/net/sf/eclipsecs/core/config/meta/MetadataFactory.java

Line 568 in 100aaca

parseMetadata(metadataStream, metadataBundle);

Installing a version of eclipse-cs on or before 8.35 seems to resolve the issue and bring back the functionality. This seems to lead to #256 to be the culprit.

There appears to be 2 issues so far:

1. eclipse-cs doesn't allow any other 3rd party groups to be added except "Other"
2. The presence of the YML file prevents violations from coming out.