Remove ES_NEXT macro (#4915)

- remove all '#JERRY_ESNEXT' macro
- remove 5.1 build profile, update test runner accordingly (Note: all builtins are turn on by default)
- move tests from tests/jerry/esnext into tests/jerry, concatenate files with same names
- add skiplist to some snapshot tests that were supported only in 5.1
- fix doxygen issues that were hidden before (bc. of es.next macro)

Co-authored-by: Martin Negyokru negyokru@inf.u-szeged.hu
JerryScript-DCO-1.0-Signed-off-by: Adam Szilagyi aszilagy@inf.u-szeged.hu

jerry-core/vm/opcodes-ecma-relational-equality.c

@@ -107,7 +107,6 @@ opfunc_instanceof (ecma_value_t left_value, /**< left value */
     return ecma_raise_type_error (ECMA_ERR_RIGHT_VALUE_OF_INSTANCEOF_MUST_BE_AN_OBJECT);
   }
 
-#if JERRY_ESNEXT
   ecma_value_t has_instance_method = ecma_op_get_method_by_symbol_id (right_value, LIT_GLOBAL_SYMBOL_HAS_INSTANCE);
   if (ECMA_IS_VALUE_ERROR (has_instance_method))
   {
@@ -131,7 +130,6 @@ opfunc_instanceof (ecma_value_t left_value, /**< left value */
 
     return ecma_make_boolean_value (has_instance);
   }
-#endif /* JERRY_ESNEXT */
 
   ecma_object_t *right_value_obj_p = ecma_get_object_from_value (right_value);
   return ecma_op_object_has_instance (right_value_obj_p, left_value);