Serialize jump target reasons after FBD

Serialization (in the form of the `revamb.jt.reasons` metadata) of the
reason why a certain address is a jump target has been moved from
`JumpTargetManager::finalizeJumpTargets` to a new function
(`JumpTargetManager::createJTReasonMD`) which is invoked after the
function boundaries detection algorithm has been run.

codegenerator.cpp

@@ -921,6 +921,8 @@ void CodeGenerator::translate(uint64_t VirtualAddress) {
     FPM.run(*MainFunction);
   }
 
+  JumpTargets.createJTReasonMD();
+
   JumpTargets.noReturn().cleanup();
 
   Translator.finalizeNewPCMarkers(CoveragePath);