sys/console: Don't show prompt when echo is off

Prompt is output on console that did not originated in application code.
This is similar to echo characters that goes out of console outside
of application decision.

This disable printing prompt when echo is turned off so console
code does not add anything to the output.

sys/console/full/src/console.c

@@ -471,6 +471,10 @@ console_prompt_set(const char *prompt, const char *line)
     }
     trailing_chars = 0;
 
+    if (!console_is_interactive) {
+        return;
+    }
+
     locked = console_lock(1000) == OS_OK;
 
     console_switch_to_prompt();