Add ability to choose arbitrary resolution for render to video

[astrodavid10]

Current fillable fields allow for the ability to type in arbitrary resolutions but a flat screen render will default to your native resolution screen size, adjusted for Windows scaling. So if you have a 1920x1080 monitor at 100% scaling, it will be 1920x1080 regardless of what you choose. If you have a 3840x2160 monitor with 150% scaling, it renders frames at 2560x1440.