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.Memory/Tracking/BitMap.cs

@@ -5,7 +5,7 @@ namespace Ryujinx.Memory.Tracking
     /// <summary>
     /// A bitmap that can check or set large ranges of true/false values at once.
     /// </summary>
-    struct BitMap
+    readonly struct BitMap
     {
         public const int IntSize = 64;