Cleanup: Animation, move AnimData API to anim_data.c/BKE_anim_data.h

The `BKE_animsys.h` and `anim_sys.c` files already had a an "AnimData
API" section. The code in that section has now been split off, and
placed into `BKE_anim_data.h` and `anim_data.c`.

All files that used to include `BKE_animsys.h` have been adjusted to
only include the animation headers they need (sometimes none).

No functional changes.

source/blender/blenkernel/intern/speaker.c

@@ -28,7 +28,6 @@
 
 #include "BLT_translation.h"
 
-#include "BKE_animsys.h"
 #include "BKE_idtype.h"
 #include "BKE_lib_id.h"
 #include "BKE_main.h"