Add movement hook to ps2_mouse (#8805)

Process mouse movement in the keymap before it is sent to the host. Example uses
include filtering noise, adding acceleration, and automatically activating a
layer. To use, define the following function in your keymap:

void ps2_mouse_moved_user(report_mouse_t *mouse_report);

tmk_core/protocol/ps2_mouse.h

@@ -20,6 +20,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <stdbool.h>
 #include "debug.h"
+#include "report.h"
 
 #define PS2_MOUSE_SEND(command, message)                                                \
     do {                                                                                \
@@ -174,4 +175,6 @@ void ps2_mouse_set_resolution(ps2_mouse_resolution_t resolution);
 
 void ps2_mouse_set_sample_rate(ps2_mouse_sample_rate_t sample_rate);
 
+void ps2_mouse_moved_user(report_mouse_t *mouse_report);
+
 #endif