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

tests/unit-core/test-to-length.c

@@ -78,11 +78,7 @@ main (void)
   ecma_free_value (negative);
 
   TEST_ASSERT (!ECMA_IS_VALUE_ERROR (result));
-#if JERRY_ESNEXT
   TEST_ASSERT (num == 0);
-#else /* !JERRY_ESNEXT */
-  TEST_ASSERT (num == 4294967270);
-#endif /* JERRY_ESNEXT */
 
   /* +infinity */
   ecma_value_t positive_infinity = ecma_make_number_value (ecma_number_make_infinity (false));
@@ -92,11 +88,7 @@ main (void)
   ecma_free_value (positive_infinity);
 
   TEST_ASSERT (!ECMA_IS_VALUE_ERROR (result));
-#if JERRY_ESNEXT
   TEST_ASSERT ((ecma_number_t) num == ECMA_NUMBER_MAX_SAFE_INTEGER);
-#else /* !JERRY_ESNEXT */
-  TEST_ASSERT (num == 0);
-#endif /* JERRY_ESNEXT */
 
   /* -infinity */
   ecma_value_t negative_infinity = ecma_make_number_value (ecma_number_make_infinity (true));