Do not allow render targets not explicitly written by the fragment shader to be modified (#3063)

* Do not allow render targets not explicitly written by the fragment shader to be modified

* Shader cache version bump

* Remove blank lines

* Avoid redundant color mask updates

* HostShaderCacheEntry can be null

* Avoid more redundant glColorMask calls

* nit: Mask -> Masks

* Fix currentComponentMask

* More efficient way to update _currentComponentMasks

Ryujinx.Graphics.OpenGL/Shader.cs

@@ -7,6 +7,7 @@ namespace Ryujinx.Graphics.OpenGL
     class Shader : IShader
     {
         public int Handle { get; private set; }
+        public bool IsFragment { get; }
 
         public Shader(ShaderStage stage, string code)
         {
@@ -22,6 +23,7 @@ namespace Ryujinx.Graphics.OpenGL
             };
 
             Handle = GL.CreateShader(type);
+            IsFragment = stage == ShaderStage.Fragment;
 
             GL.ShaderSource(Handle, code);
             GL.CompileShader(Handle);