feat: TappableSpan support (#8256)

* feat(android): clickable span

Initial support for clickable span on Android

* test: clickable-span test page

* remove console.log

* use _emit instead of notify

* rename clickable to tappable in Span

* updated NativeScript.api.md

* chore: fixing tslint errors

* chore: fixed witespacing

* moved and improved test page

* feat: tappable span iOS implementation

Co-authored-by: Eduardo Speroni <edusperoni@gmail.com>

nativescript-core/ui/text-base/span.d.ts

@@ -50,6 +50,15 @@ export class Span extends ViewBase {
      * Gets or sets the text for the span.
      */
     public text: string;
+    /**
+     * String value used when hooking to linkTap event.
+     */
+    public static linkTapEvent: string;
+
+    /**
+     * Gets if the span is tappable or not.
+     */
+    public readonly tappable: boolean;
 
     //@private
     /**
@@ -57,4 +66,4 @@ export class Span extends ViewBase {
      */
     _setTextInternal(value: string): void;
     //@endprivate
-}
+}