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/Shader/ShaderDumpPaths.cs

@@ -5,7 +5,7 @@ namespace Ryujinx.Graphics.Gpu.Shader
     /// <summary>
     /// Paths where shader code was dumped on disk.
     /// </summary>
-    struct ShaderDumpPaths
+    readonly struct ShaderDumpPaths
     {
         /// <summary>
         /// Path where the full shader code with header was dumped, or null if not dumped.