Allow choosing D3D11 adapter through User Preferences or cmdline (at least)

[sergeypdev]

Here's my use case: I'm connecting a monitor to an internal GPU while using a dedicated GPU for running graphics intensive stuff. The reason is that I want the system to stay stable even in the case of an (dedicated) gpu driver crash/reset.

Right now Rad Debugger uses the default GPU selection using D3D11CreateDevice with nullptr as the adapter, which, in my case, selects the integrated GPU.

I'm getting pretty low fps in raddbg this way, it would be nice to have an option to use a different GPU.