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

tests/jerry/object-get-own-property-names.js

@@ -62,3 +62,12 @@ assert (props.indexOf("prop") !== -1);
 assert (props.indexOf("method") !== -1);
 
 assert (props.length === 2);
+
+// Check that Object.getOwnPropertyNames does NOT include Symbols by default.
+var asd = Symbol ("asd");
+var foo = Symbol ("foo");
+var bar = Symbol ("bar");
+var result = Object.getOwnPropertyNames ({1: 5, "a": 6, [foo]: 7, [asd]: 8, [bar]: 9});
+assert (!Object.hasOwnProperty (result, foo));
+assert (!Object.hasOwnProperty (result, asd));
+assert (!Object.hasOwnProperty (result, bar));