Make structs readonly when applicable (#4002)

* Make all structs readonly when applicable. It should reduce amount of needless defensive copies

* Make structs with trivial boilerplate equality code record structs

* Remove unnecessary readonly modifiers from TextureCreateInfo

* Make BitMap structs readonly too

Ryujinx.Graphics.Gpu/Image/TextureBindingInfo.cs

@@ -7,7 +7,7 @@ namespace Ryujinx.Graphics.Gpu.Image
     /// Texture binding information.
     /// This is used for textures that needs to be accessed from shaders.
     /// </summary>
-    struct TextureBindingInfo
+    readonly struct TextureBindingInfo
     {
         /// <summary>
         /// Shader sampler target type.