Add back GetFullScript

Author: JustinGrote

src/PowerShellEditorServices/Services/TextDocument/RenameService.cs

@@ -578,6 +578,9 @@ public int CompareTo(ScriptPositionAdapter other)
     }
     public int CompareTo(Position other) => CompareTo((ScriptPositionAdapter)other);
     public int CompareTo(ScriptPosition other) => CompareTo((ScriptPositionAdapter)other);
+
+    // Required for interface implementation but not used.
+    public string GetFullScript() => throw new NotImplementedException();
 }
 
 /// <summary>