core: allow renaming & merging of trackers with config (part 1 #8355) (#8608)
* rename site field to id in yaml indexers
* add id field in c# indexers
* use id field instead of class name in c#
and fix any yaml indexers that fail the syntax checking.
the option to ignoreUnmatchedProperties was enabled for #1549 and should have been turned off again once that task was completed.
leaving it enabled caused several unexplained behaviours in indexers where some statements were ignore by cardigann despite the intentions of the writer, and were not picked up during testing.