Refactor the FT decoding for better maintenance

Replaces !998 (closed).

** Changes **

• name all ClusterTypes and put them in the event model
• revert when possible the logic of the code to if (all good) then do something rather than weeding out errors;
• create a ClusterReference namespace in the event model;
• put in one place the methods to read a raw bank and get the row in DB map
• create error counters;
• rename variables to make them hopefully clearer;
• group decoding 6, 7 and 8 when possible to reduce code repetition;
• template large cluster checking on the decoding version

** For a next MR**

• do proper error counting
• make contracts