chat-sdk: include consumer proguard rules

[teobaranga]

Description:

Include consumer Proguard rules so that applications can build with R8 and minification enabled without the risk of trimming used classes. Includes two Retrofit interfaces that are accessed by reflection.

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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? N/A

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

Tested a local publication of the chat SDK integrated into a release build of the Trainline app. The Travel Assistant feature uses it.

List manual testing steps:

• All scenarios below except for the attachment ones successfully tested.

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
• Quick Connect transfer failed should show the transfer failed event in the transcript