xep-0084/avatar: add option to open avatar directly

Change:
`/avatar me@somewhere.org` -> `/avatar get me@somewhere.org`

New:
`/avatar cmd feh`
`/avatar open me@somewhere.org`

Implement https://github.com/profanity-im/profanity/issues/1281

src/ui/console.c

@@ -2039,6 +2039,16 @@ cons_correction_setting(void)
     free(cc);
 }
 
+void
+cons_avatar_setting(void)
+{
+    char *pref = prefs_get_string(PREF_AVATAR_CMD);
+
+    cons_show("Avatar command (/avatar cmd)                                       : %s", pref);
+
+    prefs_free_string(pref);
+}
+
 void
 cons_show_connection_prefs(void)
 {

src/ui/ui.h

@@ -319,6 +319,7 @@ void cons_winpos_setting(void);
 void cons_color_setting(void);
 void cons_os_setting(void);
 void cons_correction_setting(void);
+void cons_avatar_setting(void);
 void cons_show_contact_online(PContact contact, Resource *resource, GDateTime *last_activity);
 void cons_show_contact_offline(PContact contact, char *resource, char *status);
 void cons_theme_properties(void);