Input WYSIWYG: Added description_html field, added store logic

Rolled out HTML editor field and store logic across all target entity
types. Cleaned up WYSIWYG input logic and design.
Cleaned up some injected classes while there.

app/Entities/Models/Chapter.php

@@ -15,6 +15,7 @@ use Illuminate\Support\Collection;
 class Chapter extends BookChild
 {
     use HasFactory;
+    use HasHtmlDescription;
 
     public $searchFactor = 1.2;