res_ael: Use Gosub in for loop expressions

In AEL2, if a 'for' statement contains macro* calls, like:

    for (&iterator(${TRY},A); "${A}" != ""; &iterate(A)) {

The AEL2 parser will translate these into calls to the deprecated Macro
dialplan application and use the antiquated pipe delimiter.

Instead, convert these into calls to the Gosub dialplan application and
use commas as argument separators.

ASTERISK-18593 #close
Reported by: Luke-Jr

* 'macro' in this context means AEL2 macros, not the 'Macro' application

Change-Id: I3d73716033b8e3e42e0209d355bf5f10c97045fc