common: add MovingAverage class for real-time windowed average calculation (#34569)

* add MovingAverage class for real-time windowed average calculation

* move to util.py

common/util.py

@@ -0,0 +1,24 @@
+class MovingAverage:
+  def __init__(self, window_size: int):
+    self.window_size: int = window_size
+    self.buffer: list[float] = [0.0] * window_size
+    self.index: int = 0
+    self.count: int = 0
+    self.sum: float = 0.0
+
+  def add_value(self, new_value: float):
+    # Update the sum: subtract the value being replaced and add the new value
+    self.sum -= self.buffer[self.index]
+    self.buffer[self.index] = new_value
+    self.sum += new_value
+
+    # Update the index in a circular manner
+    self.index = (self.index + 1) % self.window_size
+
+    # Track the number of added values (for partial windows)
+    self.count = min(self.count + 1, self.window_size)
+
+  def get_average(self) -> float:
+    if self.count == 0:
+      return float('nan')
+    return self.sum / self.count