Exposing ConnectionDetailsProvider in ChatSession

[haomingli2020]

Issue Number:
N/A

Description:

What are the changes? Why are we making them?
Exposing ConnectionDetailsProvider in ChatSession

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Functional backward compatibility:

Does this change introduce backwards incompatible changes? [NO]

Does this change introduce any new dependency? [NO]

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Testing:

Is the code unit tested?
Yes

Have you tested the changes with a sample UI (e.g. Android Mobile Chat Example)?
Yes

List manual testing steps:

• Add Steps below:
  Manually tested calling chatSession.getConnectionDetailsProvider().getConnectionDetails() and verified the connection token was received. Also verified a new connection token is received after background/foreground events.

Here are a list of manual test cases to run through:

• Initiating chat and connecting with an agent
• Retrieving transcript
• Disconnecting from chat
• Sending a message to the agent
  • See typing bubbles on agent side
  • See read/delivered receipt on client side
  • Receiving a message from the agent
  • See typing bubbles on client side
  • See read/delivered receipt on agent side
  • Sending an attachment to the agent (try .txt, .pdf, .jpg)
  • Preview the attachment on click
  • Receiving an attachment from the agent
  • Preview the attachment on click
• Close the application (Without ending chat) → open app again → Start chat → Should Retrieve transcript from a previous chat session

[mliao95]

Could you also update the README?