Update exe service templates to support stageless payloads

[dledda-r7]

This PR updates the exe generation of exe-service templates to support larger payloads, such as stageless payloads.

[dledda-r7]

@zeroSteiner, I have spotted an issue while working. There is something called: EXE::Inject which is a flag used to use the SegmentInjector instead of the SegmentAppender. the difference betweem them is that the injector is able to execute the payload from the section (same way as the other, by modifying the entry point). but then jumps back to the original entry point to continue the execution. i have tested with the payload windows/x64/meterpreter/reverse_tcp and is not swapping the "PAYLOD:" marker with valid opcode, so probably after jumping back the original entrypoint the thread would crash badly.