Cleanup: Correct location of node function declarations

Currently there are many function declarations in `BKE_node.h` that
don't actually have implementations in blenkernel. This commit moves
the declarations to `NOD_composite.h`, `NOD_texture.h`, and
`NOD_shader.h` instead. This helps to clarify the purpose of the
different modules.

Differential Revision: https://developer.blender.org/D13869

source/blender/blenloader/intern/versioning_260.c

@@ -78,6 +78,7 @@
 #include "IMB_imbuf.h" /* for proxy / time-code versioning stuff. */
 
 #include "NOD_common.h"
+#include "NOD_composite.h"
 #include "NOD_texture.h"
 
 #include "BLO_readfile.h"

source/blender/blenloader/intern/versioning_cycles.c

@@ -42,6 +42,8 @@
 #include "BKE_main.h"
 #include "BKE_node.h"
 
+#include "NOD_shader.h"
+
 #include "MEM_guardedalloc.h"
 
 #include "IMB_colormanagement.h"