Rework module parsing and execution (#4462)

This patch disables automatic detection of module code, and instead
requires the user to explicitly specify whether to parse a source
as a module or as a script.

To achieve this the jerry_parse API function now takes a new option
which signals that the source should be parsed as a module.

JerryScript-DCO-1.0-Signed-off-by: Dániel Bátyai daniel.batyai@h-lab.eu

tests/jerry/es.next/regression-test-issue-2975.js

@@ -16,7 +16,7 @@
 /* Import/export statements must be in the global scope. */
 var eval = eval.bind();
 try {
-  eval('import { c } from "tests/jerry/es.next/module-export-01.js";');
+  eval('import { c } from "tests/jerry/es.next/module-export-01.mjs";');
   assert (false);
 } catch (e) {
   assert (e instanceof SyntaxError);