Renderer: Fix missing shader_name; use forward declarations

* Moving over to RenderingShaderContainer, missed setting shader_name
* Use forward declaration reduces compile time when modifying
  rendering_shader_container.h from over 950s to about 10-15

servers/rendering/rendering_device.cpp

@@ -37,6 +37,7 @@
 #include "core/config/project_settings.h"
 #include "core/io/dir_access.h"
 #include "modules/modules_enabled.gen.h"
+#include "servers/rendering/rendering_shader_container.h"
 
 #ifdef MODULE_GLSLANG_ENABLED
 #include "modules/glslang/shader_compile.h"

servers/rendering/rendering_device_driver.h

@@ -49,7 +49,9 @@
 #include "core/variant/type_info.h"
 #include "servers/rendering/rendering_context_driver.h"
 #include "servers/rendering/rendering_device_commons.h"
-#include "servers/rendering/rendering_shader_container.h"
+
+class RenderingShaderContainer;
+class RenderingShaderContainerFormat;
 
 // These utilities help drivers avoid allocations.
 #define ALLOCA(m_size) ((m_size != 0) ? alloca(m_size) : nullptr)

servers/rendering/rendering_shader_container.cpp

@@ -127,6 +127,8 @@ Error RenderingShaderContainer::reflect_spirv(const String &p_shader_name, Span<
 	using RDC = RenderingDeviceCommons;
 	RDC::ShaderReflection reflection;
 
+	shader_name = p_shader_name.utf8();
+
 	const uint32_t spirv_size = p_spirv.size() + 0;
 	r_refl.resize(spirv_size);