VideoCommon: move to a 'process_fragment()' function to simplify custom shaders and provide a direct override of the tev stage logic

Source/Core/VideoCommon/ShaderCache.cpp

@@ -457,7 +457,7 @@ std::unique_ptr<AbstractShader>
 ShaderCache::CompilePixelUberShader(const UberShader::PixelShaderUid& uid) const
 {
   const ShaderCode source_code =
-      UberShader::GenPixelShader(m_api_type, m_host_config, uid.GetUidData(), {});
+      UberShader::GenPixelShader(m_api_type, m_host_config, uid.GetUidData());
   return g_gfx->CreateShaderFromSource(ShaderStage::Pixel, source_code.GetBuffer(),
                                        fmt::to_string(*uid.GetUidData()));
 }