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/parser/js/common.h

@@ -76,9 +76,7 @@ typedef enum
                                      *   (no need to allocate memory) */
   LEXER_FLAG_LATE_INIT = (1 << 3), /**< initialize this variable after the byte code is freed */
   LEXER_FLAG_ASCII = (1 << 4), /**< the literal contains only ascii characters */
-#if JERRY_ESNEXT
   LEXER_FLAG_GLOBAL = (1 << 5), /**< this local identifier is not a let or const declaration */
-#endif /* JERRY_ESNEXT */
 } lexer_literal_status_flags_t;
 
 /**