Restore a couple IChangeContext uses lost in merge

Merge conflict resolution picked ChangeContext rather than
IChangeContext for a couple of methods; this fixed that.

Author: rmunn

src/SIL.Harmony.Sample/Changes/NewWordChange.cs

@@ -10,7 +10,7 @@ public class NewWordChange(Guid entityId, string text, string? note = null, Guid
     public string? Note { get; } = note;
     public Guid? AntonymId { get; } = antonymId;
 
-    public override async ValueTask<Word> NewEntity(Commit commit, ChangeContext context)
+    public override async ValueTask<Word> NewEntity(Commit commit, IChangeContext context)
     {
         var antonymShouldBeNull = AntonymId is null || (await context.IsObjectDeleted(AntonymId.Value));
         return (new Word { Text = Text, Note = Note, Id = EntityId, AntonymId = antonymShouldBeNull ? null : AntonymId });

src/SIL.Harmony.Sample/Changes/SetTagChange.cs

@@ -8,7 +8,7 @@ public class SetTagChange(Guid entityId, string text) : Change<Tag>(entityId), I
 {
     public string Text { get; } = text;
 
-    public override ValueTask<Tag> NewEntity(Commit commit, ChangeContext context)
+    public override ValueTask<Tag> NewEntity(Commit commit, IChangeContext context)
     {
         return new(new Tag()
         {
@@ -18,7 +18,7 @@ public override ValueTask<Tag> NewEntity(Commit commit, ChangeContext context)
     }
 
 
-    public override ValueTask ApplyChange(Tag entity, ChangeContext context)
+    public override ValueTask ApplyChange(Tag entity, IChangeContext context)
     {
         entity.Text = Text;
         return ValueTask.CompletedTask;