Re-target for ES.Next (#3901)

A list of changes:
- 'es2015-subset' profile is deprecated, and an 'es.next' profile is added.
- The default profile is changed to 'es.next'
- Renamed the JERRY_ES2015 guard to JERRY_ESNEXT
- Renamed JERRY_ES2015_BUILTIN_* guards to JERRY_BUILTIN_*
- Moved es2015 specific tests to a new 'es.next' subdirectory
- Updated docs, targets, and test runners to reflect these changes

Resolves #3737.

JerryScript-DCO-1.0-Signed-off-by: Dániel Bátyai dbatyai@inf.u-szeged.hu

jerry-core/ecma/builtin-objects/ecma-builtin-internal-routines-template.inc.h

@@ -189,7 +189,7 @@ const ecma_builtin_property_descriptor_t PROPERTY_DESCRIPTOR_LIST_NAME[] =
     prop_attributes, \
     magic_string_id \
   },
-#if ENABLED (JERRY_ES2015)
+#if ENABLED (JERRY_ESNEXT)
 #define SYMBOL_VALUE(symbol, desc_magic_string_id) \
   { \
     symbol, \
@@ -211,7 +211,7 @@ const ecma_builtin_property_descriptor_t PROPERTY_DESCRIPTOR_LIST_NAME[] =
     prop_attributes, \
     ECMA_ACCESSOR_READ_WRITE (getter_builtin_id, setter_builtin_id) \
   },
-#endif /* ENABLED (JERRY_ES2015) */
+#endif /* ENABLED (JERRY_ESNEXT) */
 #include BUILTIN_INC_HEADER_NAME
   {
     LIT_MAGIC_STRING__COUNT,