feat(shortcode): add shortcode for asciinema (#779)

* Add asciinema shortcode and usage examples

* Add asciinema shortcode

* Modify

* Modify

* Modify

* Modify

* Modify

* Remove old blog post and move content to dedicated documentation

* Add remote cast file support

* Fix remote cast file support

* Modify asciinema guide

* Add asciinema controls and idleTimeLimit

* fix the play button position issue and update some details

* Remove forced /casts/ prefix, implement flexible file lookup

exampleSite/content/docs/guide/shortcodes/_index.md

@@ -27,4 +27,5 @@ Additional shortcodes provided by Hugo and Hextra:
   {{< card link="jupyter" title="Jupyter Notebook" icon="jupyter" tag="alpha" >}}
   {{< card link="others" title="Others" icon="view-grid" >}}
   {{< card link="hextra" title="Hextra" icon="view-grid" >}}
+  {{< card link="asciinema" title="Asciinema Player" icon="terminal" >}}
 {{< /cards >}}