Don't convert holdings that belong to dukes or above (ParadoxGameConverters#1320) #patch

closes ParadoxGameConverters#1310 

Before:

![obraz](https://user-images.githubusercontent.com/29546927/236640927-acd770b1-ccc4-4663-8964-242b45efed86.png)
Noticeable oddities:
- Assyria
- Myos Hormos

After:

![obraz](https://user-images.githubusercontent.com/29546927/236641159-ad5804f2-b0c1-47cf-9496-e42679991c71.png)

Author: IhateTrains

ImperatorToCK3/CK3/Titles/LandedTitles.cs

@@ -458,6 +458,13 @@ public void ImportImperatorHoldings(ProvinceCollection ck3Provinces, Imperator.C
 				.Select(t=>t.CapitalCounty?.CapitalBaronyId ?? t.CapitalBaronyId)
 				.ToImmutableHashSet();
 
+			// Dukes and above should be excluded from having their holdings converted.
+			// Otherwise, governors with holdings would own parts of other governorships.
+			var dukeAndAboveIds = titlesThatHaveHolders
+				.Where(t => t.Rank >= TitleRank.duchy)
+				.Select(t => t.GetHolderId(conversionDate))
+				.ToImmutableHashSet();
+			
 			var baronies = this.Where(t => t.Rank == TitleRank.barony).ToImmutableHashSet();
 			var countyCapitalBaronies = baronies
 				.Where(b => b.DeJureLiege?.CapitalBaronyId == b.Id)
@@ -492,6 +499,9 @@ public void ImportImperatorHoldings(ProvinceCollection ck3Provinces, Imperator.C
 				if (ck3Owner is null) {
 					continue;
 				}
+				if (dukeAndAboveIds.Contains(ck3Owner.Id)) {
+					continue;
+				}
 
 				var realm = ck3Owner.ImperatorCharacter?.HomeCountry?.CK3Title;
 				var deFactoLiege = realm;