common: add MovingAverage class for real-time windowed average calculation

[deanlee]

This PR replaces the previous deque-based moving average calculation with a new MovingAverage class using a fixed-size circular buffer. This improves performance by reducing memory overhead and making updates more efficient.

Key Changes:

1. Replaced Deque with Circular Buffer: The deque used to store recent values has been replaced by a circular buffer, eliminating the need for append and pop operations.
2. Constant Time Updates: Adding new values and updating the average now happens in constant time, regardless of the window size, by maintaining a running sum.
3. Lower Memory Overhead: By using a fixed-size buffer, we reduce the overhead of dynamic memory allocation and deallocation associated with the deque.

This PR also enhances the Ratekeeper.lagging check, which is invoked multiple times in selfdrived, by eliminating redundant sum calculations,

[adeebshihadeh]

why do we need to add a value every time?

[deanlee]

Add an initial value in __init__ because ratekeeper calls lagging() before it updates with monitor_time(). This ensures the first call to lagging() returns a valid average, avoiding uninitialized values, similar to how self._dts = deque([self._interval], maxlen=100) works by starting with an initial value.