Support ignore all santize for external renderer (#18984)

* Support ignore all santize for external renderer

* Update docs

* Apply suggestions from code review

Co-authored-by: silverwind <me@silverwind.io>

* Fix doc

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: 6543 <6543@obermui.de>

modules/markup/markdown/markdown.go

@@ -221,6 +221,11 @@ func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
 	return []setting.MarkupSanitizerRule{}
 }
 
+// SanitizerDisabled disabled sanitize if return true
+func (Renderer) SanitizerDisabled() bool {
+	return false
+}
+
 // Render implements markup.Renderer
 func (Renderer) Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
 	return render(ctx, input, output)