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.HLE/HOS/Kernel/Process/ProcessCreationInfo.cs

@@ -1,6 +1,6 @@
 namespace Ryujinx.HLE.HOS.Kernel.Process
 {
-    struct ProcessCreationInfo
+    readonly struct ProcessCreationInfo
     {
         public string Name { get; }