Rework external function handlers (#4599)

Instead of a fixed number of arguments, a call info structure is passed
to the handlers, which can be extended in the future without breaknig the
API. This structure holds new.target value, so its getter function is removed.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/unit-ext/test-ext-method-register.c

@@ -24,13 +24,11 @@
 #include <string.h>
 
 static jerry_value_t
-method_hello (const jerry_value_t jfunc,  /**< function object */
-              const jerry_value_t jthis,  /**< function this */
+method_hello (const jerry_call_info_t *call_info_p, /**< call information */
               const jerry_value_t jargv[], /**< arguments */
               const jerry_length_t jargc) /**< number of arguments */
 {
-  (void) jfunc;
-  (void) jthis;
+  (void) call_info_p;
   (void) jargv;
   return jerry_create_number (jargc);
 } /* method_hello */