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/include/jerryscript-port.h

@@ -197,7 +197,7 @@ void jerry_port_print_char (char c);
  * Open a source file and read its contents into a buffer.
  *
  * Note:
- *      This port function is called by jerry-core when JERRY_ES2015_MODULE_SYSTEM
+ *      This port function is called by jerry-core when JERRY_MODULE_SYSTEM
  *      is enabled. The path is specified in the import statement's 'from "..."'
  *      section.
  *
@@ -221,7 +221,7 @@ void jerry_port_release_source (uint8_t *buffer_p);
  * Normalize a file path string.
  *
  * Note:
- *      This port function is called by jerry-core when ES2015_MODULE_SYSTEM
+ *      This port function is called by jerry-core when JERRY_MODULE_SYSTEM
  *      is enabled. The normalized path is used to uniquely identify modules.
  *
  * @param in_path_p Input path as a zero terminated string.
@@ -242,7 +242,7 @@ size_t jerry_port_normalize_path (const char *in_path_p,
  * Get the module object of a native module.
  *
  * Note:
- *      This port function is called by jerry-core when ES2015_MODULE_SYSTEM
+ *      This port function is called by jerry-core when JERRY_MODULE_SYSTEM
  *      is enabled.
  *
  * @param name String value of the module specifier.