Refactor: Move ReportList definition from DNA to blenkernel

Ever since [0], ReportList is not actually used in any DNA structs.
That makes sense, since reports are conceptually only necessary
at runtime. Move the definition of the struct to BKE_report.hh, and
fix a bunch of include errors where types were previously available
transitively. Besides adding some clarity, theoretically this change
could reduce compile times because of less header parsing.

[0]: 1bf6d8b0b9

Pull Request: https://projects.blender.org/blender/blender/pulls/138872

source/blender/python/intern/bpy_rna.cc

@@ -53,6 +53,8 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "DNA_windowmanager_types.h"
+
 #include "BKE_context.hh"
 #include "BKE_global.hh" /* evil G.* */
 #include "BKE_idprop.hh"