[Request]: Show reply-to post & media when editing alt in composer

[GeopJr]

Describe the request

Post you are replying to should be visible in the composer. Media attachment you are adding alt text to should also be visible.

Implementation Details

• [ ] This should be an option in settings.
• [ ] This should be only available to some fediverse backends. (Include which ones on the above field).
• [ ] This is client-only (and shouldn't sync with the instance).
• [X] This follows the GNOME HIG.