RenderSystem, RenderContext, VideoMode refactor

[LukasBanana]

RenderSystem interface should be renamed to Device and RenderContext should be renamed to SwapChain. Along this renaming, the RenderContextDescriptor, VsyncDescriptor and VideoModeDescriptor should be merged into SwapChainDescriptor like this:

Before:

struct VsyncDescriptor {
    bool            enabled     = false;
    std::uint32_t   refreshRate = 60;
    std::uint32_t   interval    = 1;
};

struct VideoModeDescriptor {
    Extent2D        resolution;
    int             colorBits       = 32;
    int             depthBits       = 24;
    int             stencilBits     = 8;
    bool            fullscreen      = false;
    std::uint32_t   swapChainSize   = 2;
};

struct RenderContextDescriptor {
    VsyncDescriptor         vsync;
    std::uint32_t           samples     = 1;
    VideoModeDescriptor     videoMode;
};

After:

struct SwapChainDescriptor {
    Extent2D        resolution;
    int             colorBits       = 32;
    int             depthBits       = 24;
    int             stencilBits     = 8;
    bool            fullscreen      = false;
    std::uint32_t   swapBuffers     = 2;
//  std::uint32_t   refreshRate     = 60; // Refresh rate is display dependent and should not be an option here
    std::uint32_t   samples         = 1;
    std::uint32_t   vsyncInterval   = 0;
};

[LukasBanana]

This is mostly done now with commit e3622eb:

• RenderContext interface was renamed to SwapChain.
• VsyncDescriptor, VideoModeDescriptor, and RenderContextDescriptor were merged into SwapChainDescriptor.
• RenderContext::SetVideoMode is replaced by SwapChain::ResizeBuffers.