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-arithmetics.c

@@ -105,13 +105,11 @@ do_number_arithmetic (number_arithmetic_op op, /**< number arithmetic operation
         result = ecma_number_remainder (left_number, right_number);
         break;
       }
-#if JERRY_ESNEXT
       case NUMBER_ARITHMETIC_EXPONENTIATION:
       {
         result = ecma_number_pow (left_number, right_number);
         break;
       }
-#endif /* JERRY_ESNEXT */
     }
 
     ret_value = ecma_make_number_value (result);
@@ -150,13 +148,11 @@ do_number_arithmetic (number_arithmetic_op op, /**< number arithmetic operation
         ret_value = ecma_bigint_div_mod (left_value, right_value, true);
         break;
       }
-#if JERRY_ESNEXT
       case NUMBER_ARITHMETIC_EXPONENTIATION:
       {
         ret_value = ecma_bigint_pow (left_value, right_value);
         break;
       }
-#endif /* JERRY_ESNEXT */
     }
 
     ecma_free_value (left_value);