InstructionSerializer split into separate serializers

 - updated initialization of default Action and Instruction experimenter serializers
 - CodingUtils replaced by ListSerializer
 - added EnhancedTypeKeyMaker classes to create lookup keys
 - added InstructionConstants
 - updated unit tests

Signed-off-by: Michal Polkorab <michal.polkorab@pantheon.sk>
Change-Id: If27b8273aadc84ec93e90fbb08326cf7baeb3645