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-async-function.c

@@ -15,8 +15,6 @@
 
 #include "ecma-globals.h"
 
-#if JERRY_ESNEXT
-
 #define ECMA_BUILTINS_INTERNAL
 #include "ecma-builtins-internal.h"
 #include "ecma-function-object.h"
@@ -68,5 +66,3 @@ ecma_builtin_async_function_dispatch_construct (const ecma_value_t *arguments_li
  * @}
  * @}
  */
-
-#endif /* JERRY_ESNEXT */