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/operations/ecma-symbol-object.c

@@ -26,8 +26,6 @@
 
 #include "lit-char-helpers.h"
 
-#if JERRY_ESNEXT
-
 /** \addtogroup ecma ECMA
  * @{
  *
@@ -172,7 +170,6 @@ ecma_symbol_this_value (ecma_value_t this_arg) /**< this argument value */
   /* 3. */
   return ecma_raise_type_error (ECMA_ERR_ARGUMENT_THIS_NOT_SYMBOL);
 } /* ecma_symbol_this_value */
-#endif /* JERRY_ESNEXT */
 
 /**
  * @}