Provide support to add the XSS syntax with existing html sanitizer list Validated

Customer Requirement:

The customer wants to add any tags/selectors to the already existing html sanitizer tags/selectors.

Current Behavior:

Currently there is no option to add extra(customer need) tags/selectors to the filter, so that the tags can be prevented in the Rich Text Editor.

We have “DeniedSanitizeSelectors” API which removes the tags/selectors from the html sanitizer list, so that configured tags can be allowed.

For Example:

<SfRichTextEditor EnableHtmlSanitizer="true" DeniedSanitizeSelectors="@FilterElements">

    <p>Ric<a href="<script>fds</script>">google</a>h Text Ed  <iframe src=http://evil.com/xss.html></iframe>itor allows to insert images from online source as well as local computer where you want to insert the image in your content.</p>

</SfRichTextEditor>

@code { public string[] FilterElements { get; set; } = new string[] { "iframe[src]" }; }

Here by default when the EnableHtmlSanitizer is true the iframe will removed when RTE is rendered. But when the “iframe[src]” selector is added to the  DeniedSanitizeSelectors list, it will allowed to rendered.

Likewise we need a API property to add customer required selectors/tag to the already existing list.