Make bot avatar upload work like other image uploads

[alya]

Currently, the bot avatar management UI works differently from all other avatar/profile image upload UIs. For consistency of experience and ease of maintenance, we should make bot avatar management work like other profile image uploads, including:

• The profile image preview acts as an upload button.
• On-hover text explaining how to upload, and x to delete the image. If the avatar ends up being too small, we can show the upload info in a tooltip instead.
• Changes are saved right away, without needing to click the "Save changes" button.

The avatar can be sized up and shown alongside the editable fields in the "Manage bot" modal. We should discuss and finalize the plan for any changes in the avatar placement before doing any work on this part of the issue. Note that we may redesign the "Profile" tab to have the avatar on the left.

Follow-ups

• We'll probably want to add the same avatar display and management UI to the "Manage user" panel for non-bot users.

Related issues

• Fix behavior when editing bot avatar. #24427

Screenshots

CZO thread

[zulipbot]

Hello @zulip/server-bots, @zulip/server-settings members, this issue was labeled with the "area: bots", "area: settings UI" labels, so you may want to check it out!