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.Audio.Backends.SoundIo/Native/libsoundio/SoundIOSampleRateRange.cs

@@ -1,6 +1,6 @@
 namespace SoundIOSharp
 {
-    public struct SoundIOSampleRateRange
+    public readonly struct SoundIOSampleRateRange
     {
         internal SoundIOSampleRateRange(int min, int max)
         {