Add crate.destroy() and widget.destroy()

[halid96]

1️⃣ Please provide an API to manually stop and start the chat data sync...

We may don't need chat data sync when:

• The users are in other tabs, other websites
• The embedded widget is hidden

This can be a bandwidth issue for those with slow internet, it's not necessary to fetch megabytes of images every second when the chat is hidden for hours.. 😊