run0: optionally show superhero emoji on each shell prompt

This makes use of the infra introduced in 229d4a9806 to indicate visually on each prompt that we are in superuser mode temporarily.
pick ad5de3222f userdbctl: add some basic client-side filtering

src/basic/glyph-util.h

@@ -55,6 +55,7 @@ typedef enum SpecialGlyph {
         SPECIAL_GLYPH_YELLOW_CIRCLE,
         SPECIAL_GLYPH_BLUE_CIRCLE,
         SPECIAL_GLYPH_GREEN_CIRCLE,
+        SPECIAL_GLYPH_SUPERHERO,
         _SPECIAL_GLYPH_MAX,
         _SPECIAL_GLYPH_INVALID = -EINVAL,
 } SpecialGlyph;