Add ExtendedCall to PLCObject as a replacement of RemoteExec and reflect it in eRPC interface.

ExtendedCall is a generic remote procedure call that runtime code can register to and that IDE extensions can call.
For example a fieldbus extension can use ExtendedCall to browse the fieldbus devices connected to the runtime.

<?xml version='1.0' encoding='utf-8'?>
<BeremizRoot URI_location="ERPC://localhost:61131">
  <TargetType/>
  <Libraries Enable_Native_Library="true" Enable_Python_Library="false"/>
</BeremizRoot>