Add .exe-based injection methods

Create a method of injection by launching an exe, similar to thprac and others.

For ease of understanding and introduction.

Injection by d3d9.dll is also retained.

Implemented in 4530347774ae053def53c14ae3787742dcc02c35.

But injecting without dll has not yet been realized. I'm going to trace thprac's implementation, but I don't know if that will work.

I decided I didn't need to do anything more than this.