Code cleanup for app and SDK

[mrajatttt]

Issue Number:

Description:

What are the changes? Why are we making them?

• Code cleanup
• Added license header to missing files
• Organised file a little bit
• No code or breaking changes, Unit tests are passing, also tested app.

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Functional backward compatibility:

Does this change introduce backwards incompatible changes? [YES/NO]

Does this change introduce any new dependency? [YES/NO]

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Testing:

Is the code unit tested?

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

List manual testing steps:

• Add Steps below:

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