Fixed issue with automatic config variant selection, where we were not properly handling XMEGA targets with the JTAG physical interface.

Also introduced new AVR8 families, for D series targets.
Also moved AVR family param outside of TargetParameters struct

src/Targets/Microchip/AVR/AVR8/TargetDescription/TargetDescriptionFile.cpp

@@ -141,9 +141,9 @@ Family TargetDescriptionFile::getFamily() const {
         throw Exception("Could not find target family name in target description file.");
     }
 
-    if (familyNameToEnums.find(familyName) == familyNameToEnums.end()) {
+    if (!familyNameToEnums.contains(familyName)) {
         throw Exception("Unknown family name in target description file.");
     }
 
-    return familyNameToEnums.find(familyName)->second;
+    return familyNameToEnums.at(familyName);
 }