New functions:
- ecma_create_symbol
- ecma_value_is_symbol
- jerry_get_symbol_descriptive_string
Also improve the jerryx_handler_print to be able to print symbol values via using the jerry_get_symbol_descriptive_string API function for symbol values.
JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu