update models to use new ModelBase

Oqtane.Shared/Modules/HtmlText/Models/HtmlText.cs

@@ -7,16 +7,11 @@ using Oqtane.Documentation;
 namespace Oqtane.Modules.HtmlText.Models
 {
     [PrivateApi("Mark HtmlText classes as private, since it's not very useful in the public docs")]
-    public class HtmlText : IAuditable
+    public class HtmlText : ModelBase
     {
         [Key]
         public int HtmlTextId { get; set; }
         public int ModuleId { get; set; }
         public string Content { get; set; }
-
-        public string CreatedBy { get; set; }
-        public DateTime CreatedOn { get; set; }
-        public string ModifiedBy { get; set; }
-        public DateTime ModifiedOn { get; set; }
     }
 }