Refactor AbstractDBBuilder hierarchy and check if targetDbFile needs to be explicitly set as writable

[marekhorst]

It looks like all implementations of AbstractDBBuilder#initializeProcess() in the following subclasses:

• CommunityDBBuilder
• DatasetDBBuilder
• ServiceDBBuilder
• PatentDBBuilder
• ProjectDBBuilder
• ResearchInitiativeDBBuilder
• SoftwareHeritageOriginDBBuilder

are quite similar and it should be possible to refactor it and put most of the code in a shared method.

We should also check if targetDbFile.setWritable(true); is really needed and justified since it doesn't work for non-existing files. We should check if it is possible this file could be already created e.g. by previous execution of this process on the same datanode. This was referenced in #1398 (comment) as a part of CR process.