[EDU-1657] - Adding typing indicator with Ably Chat

[GregHolmes]

Description

This PR contains the two code samples for the new Examples section we are creating. It contains a Typescript and a React version for Typing indicator with Chat. Which will be rendered in the code sandbox live examples in the future, along with others.

The README within each directory /examples/chat-typing-indicator/javascript and /examples/chat-typing-indicator/react contains information on how to get these running.

• Jira epic ticket
• Jira ticket.

[GregHolmes]

Thank you @splindsay-92 and @vladvelici , I've updated the code for both examples based on your feedbacks.