Translate a few simple Core Data model types into Swift (#24983)

* Translate MenuLocation to Swift

* Translate PostCategory to Swift

* Translate PostTag to Swift

* Translate PostType to Swift

* Translate SourcePostAttribution to Swift

* Translate ReaderGapMarker to Swift

* Remove unused constants

* Rename PostCateogyr.uncategorizedId to uncategorized

Author: crazytonyli

Sources/WordPressData/Objective-C/Menu.m

@@ -1,6 +1,5 @@
 #import "Menu.h"
 #import "MenuItem.h"
-#import "MenuLocation.h"
 #import "Blog.h"
 
 NSInteger const MenuDefaultID = -1;

Sources/WordPressData/Objective-C/MenuItem.m

@@ -1,7 +1,7 @@
 #import "MenuItem.h"
 #import "Menu.h"
-#import "PostType.h"
 #import "Blog.h"
+#import "WordPressData-Swift.h"
 
 NSString * const MenuItemTypePage = @"page";
 NSString * const MenuItemTypeCustom = @"custom";

Sources/WordPressData/Objective-C/MenuLocation.m

@@ -1,7 +1,6 @@
 #import "Blog.h"
 #import "PostService.h"
 #import "PostServiceOptions.h"
-#import "PostCategory.h"
 #import "Media.h"
 #import "WordPressData-Swift.h"
 #import "PostHelper.h"

Sources/WordPressData/Objective-C/PostCategory.m

@@ -1,5 +1,4 @@
 #import "ReaderPost.h"
-#import "SourcePostAttribution.h"
 #import "WPAccount.h"
 #import "WordPressData-Swift.h"
 
@@ -223,13 +222,13 @@ + (SourcePostAttribution *)createOrReplaceFromRemoteDiscoverAttribution:(RemoteS
 + (NSString *)attributionTypeFromTaxonomies:(NSArray *)taxonomies
 {
     if ([taxonomies containsObject:SourceAttributionSiteTaxonomy]) {
-        return SourcePostAttributionTypeSite;
+        return SourcePostAttribution.site;
     }
 
     if ([taxonomies containsObject:SourceAttributionImageTaxonomy] ||
         [taxonomies containsObject:SourceAttributionQuoteTaxonomy] ||
         [taxonomies containsObject:SourceAttributionStandardTaxonomy] ) {
-        return SourcePostAttributionTypePost;
+        return SourcePostAttribution.post;
     }
 
     return nil;
@@ -358,9 +357,9 @@ - (NSString *)likeCountForDisplay
 
 - (SourceAttributionStyle)sourceAttributionStyle
 {
-    if ([self.sourceAttribution.attributionType isEqualToString:SourcePostAttributionTypePost]) {
+    if ([self.sourceAttribution.attributionType isEqualToString:SourcePostAttribution.post]) {
         return SourceAttributionStylePost;
-    } else if ([self.sourceAttribution.attributionType isEqualToString:SourcePostAttributionTypeSite]) {
+    } else if ([self.sourceAttribution.attributionType isEqualToString:SourcePostAttribution.site]) {
         return SourceAttributionStyleSite;
     } else {
         return SourceAttributionStyleNone;