Description:

When a room/channel avatar is updated on the Rocket.Chat server, the Embedded Chat header still shows the fix avatar image.

Steps to reproduce:

1. Change a room’s/channel's avatar in the Rocket.Chat by clicking on the avatar and editing it.
2. Open the Embedded Chat interface and try to refresh it.
3. Notice that the channel avatar in the header does not update.

Expected behavior:

The header should display the updated avatar immediately after the change. This could be achieved by appending an ETag (or cache-busting parameter) to the avatar URL and also correcting the getChannelAvatarURL function which is using wrong predefined url.

Actual behavior: