feat: Implement color coded status messages for file transfers

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>

src/ui/ui.h

@@ -25,12 +25,14 @@
 #include "otr/otr.h"
 #endif
 
-#define NO_ME          1
-#define NO_DATE        2
-#define NO_EOL         4
-#define NO_COLOUR_FROM 8
-#define NO_COLOUR_DATE 16
-#define UNTRUSTED      32
+#define NO_ME           1
+#define NO_DATE         2
+#define NO_EOL          4
+#define NO_COLOUR_FROM  8
+#define NO_COLOUR_DATE  16
+#define UNTRUSTED       32
+#define ENTRY_COMPLETED 64
+#define ENTRY_ERROR     128
 
 // core UI
 void ui_init(void);