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

docs/10.EXT-REFERENCE-HANDLER.md

@@ -267,8 +267,7 @@ jerryx_set_properties (const jerry_value_t target_object,
 #include "jerryscript-ext/handler.h"
 
 static jerry_value_t
-handler (const jerry_value_t function_obj,
-         const jerry_value_t this_val,
+handler (const jerry_call_info_t *call_info_p,
          const jerry_value_t args_p[],
          const jerry_length_t args_cnt)
 {
@@ -331,8 +330,7 @@ when setting a property entry:
 #include "jerryscript-ext/handler.h"
 
 static jerry_value_t
-handler (const jerry_value_t function_obj,
-         const jerry_value_t this_val,
+handler (const jerry_call_info_t *call_info_p,
          const jerry_value_t args_p[],
          const jerry_length_t args_cnt)
 {