imu: make it part of InputState

Putting this here to see what CI has to say. Not super happy with this, input state seems to expand/copy too much

python_payload/apps/demo_imu/__init__.py

-# python imports
-import random
-import time
-import math
-
 # flow3r imports
 from st3m import InputState
 from st3m.application import Application
-from st3m.property import BLUE, WHITE
-from st3m.goose import Optional
 from ctx import Context
 from st3m.utils import tau
 
@@ -32,8 +25,8 @@ class IMUDemo(Application):
     def think(self, ins: InputState, delta_ms: int) -> None:
         super().think(ins, delta_ms)
 
-        self.v_y += ins.acc[0] * delta_ms / 1000.0 * 10
-        self.v_x += ins.acc[1] * delta_ms / 1000.0 * 10
+        self.v_y += ins.imu.acc[0] * delta_ms / 1000.0 * 10
+        self.v_x += ins.imu.acc[1] * delta_ms / 1000.0 * 10
 
         x = self.p_x + self.v_x * delta_ms / 1000.0
         y = self.p_y + self.v_y * delta_ms / 1000.0
@@ -44,6 +37,3 @@ class IMUDemo(Application):
         else:
             self.v_x = 0
             self.v_y = 0
-
-
-app = IMUDemo("imu")