Introduce meaningful color feedback for background tasks like file
downloads and uploads. Progress is displayed in a neutral color,
while successful completions turn green and failures turn red.
We reuse the existing THEME colors for now.
Add new UI flags ENTRY_COMPLETED and ENTRY_ERROR to
the buffer entry system. So we don't misuse delivery receipts anymore.
Fixes: https://github.com/profanity-im/profanity/issues/1758
Signed-off-by: Michael Vetter <jubalh@iodoru.org>
63af72773c