Fix various hints and warnings on many set & block classes (via IntelliJ IDEA linting):

- replacing hard coded strings of set codes with reference to 'mage.sets.<set>.getInstance().getCode()' allows for set class names to no longer show as unreferenced & adds for more consistence between other block units
- various protected variables were able to be changed to private to clean up additional warnings
- some JavaDoc comments were generating warnings due to missing documentation
- removed some unused imports and unused variables
- there were multiple conditional logic checks for 'rarity != Rarity.LAND' within an if block where the outer condition was 'if rarity == Rarity.COMMON' rendering the inner condition always true and thus redundant
- a few ExpansionSet.buildDate parameters wer using octal values (eg. '03' instead of '3') which triggered some warnings
- added a booster generation test for WarOfTheSparks to make sure every booster contains a planeswalker
- added a booster generation test for ModernHorizons to make sure every booster contains a snow land
- booster generation test for Battlbond set referenced the Coldsnap set class instead of Battlebond

Mage.Sets/src/mage/sets/ShadowsOverInnistrad.java

@@ -25,7 +25,7 @@ public final class ShadowsOverInnistrad extends ExpansionSet {
         return instance;
     }
 
-    protected final EnumMap<Rarity, List<CardInfo>> savedDoubleFacedCards;
+    private final EnumMap<Rarity, List<CardInfo>> savedDoubleFacedCards;
 
     private ShadowsOverInnistrad() {
         super("Shadows over Innistrad", "SOI", ExpansionSet.buildDate(2016, 4, 8), SetType.EXPANSION);
@@ -387,7 +387,7 @@ public final class ShadowsOverInnistrad extends ExpansionSet {
         }
     }
 
-    public List<CardInfo> getDoubleFacedCardsByRarity(Rarity rarity) {
+    private List<CardInfo> getDoubleFacedCardsByRarity(Rarity rarity) {
         List<CardInfo> savedCardsInfos = savedDoubleFacedCards.get(rarity);
         if (savedCardsInfos == null) {
             CardCriteria criteria = new CardCriteria();