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.Vulkan/HardwareCapabilities.cs

@@ -2,7 +2,7 @@
 
 namespace Ryujinx.Graphics.Vulkan
 {
-    struct HardwareCapabilities
+    readonly struct HardwareCapabilities
     {
         public readonly bool SupportsIndexTypeUint8;
         public readonly bool SupportsCustomBorderColor;