[MovingWindow] Add a trigger that fires after having received a fixed number of samples

[matthias-wende-frequenz]

What's needed?

Currently there is no clean way to wait until the MovingWindow got updated with a certain number of samples.
This feature has been requested in the past and there has been an initial implemented attempt #387.

This feature has been requested again now by @cwasicki.

Proposed solution

Introduce an asynchronous wait_for_samples method that returns once the requested number of new samples has been stored in the MovingWindow.

Use cases

• replace a while loop in the Forecast actor (Add method to MovingWindow that waits for a number of samples #387 (comment))

Alternatives and workarounds

No response

Additional context

No response