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/ecma/builtin-objects/ecma-builtin-referenceerror.c

@@ -67,9 +67,6 @@ ecma_value_t
 ecma_builtin_reference_error_dispatch_construct (const ecma_value_t *arguments_list_p, /**< arguments list */
                                                  uint32_t arguments_list_len) /**< number of arguments */
 {
-#if !JERRY_ESNEXT
-  return ecma_builtin_reference_error_dispatch_call (arguments_list_p, arguments_list_len);
-#else /* JERRY_ESNEXT */
   ecma_object_t *proto_p = ecma_op_get_prototype_from_constructor (JERRY_CONTEXT (current_new_target_p),
                                                                    ECMA_BUILTIN_ID_REFERENCE_ERROR_PROTOTYPE);
 
@@ -89,7 +86,6 @@ ecma_builtin_reference_error_dispatch_construct (const ecma_value_t *arguments_l
   ecma_deref_object (proto_p);
 
   return result;
-#endif /* JERRY_ESNEXT */
 } /* ecma_builtin_reference_error_dispatch_construct */
 
 /**