Set screen resolution when open stream window

[kelvin8906]

Is your feature request related to a problem? Please describe.
My PC is using UHD 620 which is a "low power" NUC. My ordinary resolution is set to 4k, but when using any streaming tool, it use a engine (opengl/valkan/etc) to render decoded frame. Thus makes the graphic stutter dealing with 4k texture surface.

Describe the solution you'd like
In video - window type, it is better to add an option call (Forced fullscreen) or (Fixed resolution fullscreen). Before entering stream session, set the window resolution to target resolution. When steam ends, rollback to previous resolution.

Describe alternatives you've considered
People using integrated graphics can also set resolution to 1080p mannually, it can also do the tricks.

[streetpea]

@kelvin8906 I guess you are talking about switching the resolution at the screen level. That would require using the OS APIs to do so I guess. If you want to work on that feel free as it's open source. Otherwise, I'm not super keen to add something like this.