Rendered the user avatars in the chat screen. An important thing to note about this diff vs D7067 is that since web has a lot more screen real estate than native, I DID NOT reduce the width of chat bubbles. I thought about it at first; however, after seeing how the chat screen looked visually with the avatar, I felt that it was unnecessary to reduce the width of the chat bubbles as we did in native

Depends on D7194

Please look at the screenshots below to see the changes I made (only handles the user avatars in the chat screen and none of the thread avatars shown in the UI--- those will come later in the stack)

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After:

Under the hood:

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Responsiveness:

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Responsiveness with super thin photos:

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After: