Add InitNativeDebug API

This PR adds the API functions InitNativeDebug and InitNativeDebugW for executables that cannot be started with CreateProcess. For the reasons for this PR refer to x64dbg #1656.

While the process creation capabilities are a strict superset of InitDebug and InitDLLDebug (it can create a process out of pretty much any file so long as it starts with "MZ"), it is mainly intended for native executables or PE files with subsystem types other than CLI/GUI, hence the name. Debugging regular executables gives varying results: console applications seem to work OK, GUI applications will generally fail unless they are extremely simple. (More details about why this is in the x64dbg thread.)