tools: Allow running unit tests from command line

Add argument parsing to unit_test.py to allow running unit tests from
command line.

tools/unit-test-app/components/unity/unity_platform.c

@@ -309,6 +309,7 @@ static int print_test_menu(void)
             }
          }
      }
+     printf("\nEnter test for running.\n"); /* unit_test.py needs it for finding the end of test menu */
      return test_counter;
 }