Debloat IVideoDriver and IrrlichtDevice includes (#15080)

As the project grows, compile time will not go down unless the header mess
is cleaned up one by one to only include exactly what's needed.

src/client/shadows/dynamicshadows.cpp

@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/clientenvironment.h"
 #include "client/clientmap.h"
 #include "client/camera.h"
+#include <IVideoDriver.h>
 
 using m4f = core::matrix4;
 

src/client/shadows/dynamicshadowsrender.cpp

@@ -32,6 +32,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "EShaderTypes.h"
 #include "IGPUProgrammingServices.h"
 #include "IMaterialRenderer.h"
+#include <IVideoDriver.h>
 
 ShadowRenderer::ShadowRenderer(IrrlichtDevice *device, Client *client) :
 		m_smgr(device->getSceneManager()), m_driver(device->getVideoDriver()),

src/client/shadows/dynamicshadowsrender.h

@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include <string>
 #include <vector>
+#include <IrrlichtDevice.h>
 #include "irrlichttypes_extrabloated.h"
 #include "client/shadows/dynamicshadows.h"
 

src/client/shadows/shadowsScreenQuad.cpp

@@ -18,6 +18,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 
 #include "shadowsScreenQuad.h"
+#include <IVideoDriver.h>
 
 shadowScreenQuad::shadowScreenQuad()
 {