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

+# flow3r imports
+from st3m import InputState
+from st3m.application import Application, ApplicationContext
+from ctx import Context
+from st3m.utils import tau
+
+
+class IMUDemo(Application):
+    def __init__(self, app_ctx: ApplicationContext) -> None:
+        super().__init__(app_ctx)
+        self.v_x = 0.0
+        self.v_y = 0.0
+        self.p_x = 0.0
+        self.p_y = 0.0
+
+    def draw(self, ctx: Context) -> None:
+        ctx.rectangle(-120, -120, 240, 240)
+        ctx.rgb(0, 0, 0)
+        ctx.fill()
+
+        ctx.arc(self.p_x, self.p_y, 10, 0, tau, 0)
+        ctx.rgb(117 / 255, 255 / 255, 226 / 255)
+        ctx.fill()
+
+    def think(self, ins: InputState, delta_ms: int) -> None:
+        super().think(ins, delta_ms)
+
+        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
+
+        if x**2 + y**2 < (120 - 10) ** 2:
+            self.p_x = x
+            self.p_y = y
+        else:
+            self.v_x = 0
+            self.v_y = 0