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/regexp/re-bytecode.h

@@ -82,9 +82,7 @@ typedef enum
 
   RE_OP_CLASS_ESCAPE, /**< class escape */
   RE_OP_CHAR_CLASS, /**< character class */
-#if JERRY_ESNEXT
   RE_OP_UNICODE_PERIOD, /**< period in full unicode mode */
-#endif /* JERRY_ESNEXT */
   RE_OP_PERIOD, /**< period in non-unicode mode */
   RE_OP_CHAR, /**< any code point */
   RE_OP_BYTE, /**< 1-byte utf8 character */