Improvements

• Switched to font-awesome v5 icons for the default icons set.
• Moved HtmlHelper methods into a trait for easier usage from project level if one extends already another HtmlHelper extension (e.g. Bootstrap one)
• Moved UrlHelper methods into a trait for easier usage from project level if one extends already another UrlHelper extension (e.g. Bootstrap one)
• Add admin backend for icon testing of FormHelper
• Allow Bitmasked behavior to be applied on afterMarshal
• CakePHP 4.1+ now