Add StatisticsAggregator API

[TjarkMiener]

This PR adds a skeleton API for the statistical calculation of pixel-wise values over a given time interval. The current implementation features two different extraction methods, i.e. a PlainExtractor based on numpy functions and SigmaClippingExtractor based on astropy functions, which are also used in lstchain.

I'm marking this PR as a draft because of the following discussion points:

1. How to implement the unit tests? I would propose to create random distributions with a given mean and std to assert the correctness of the extraction components.
2. How to deal with the last data chunk that is calculated with fewer samples as requested? Skip it or take the last samples fulfilling the sample_size?
3. Allow overlapping chunks of samples? How to define the validity range (using start-stop or only start)?

Related to #2542.

[TjarkMiener]

I'm having some troubles with ruff, which makes pylint fail. Can someone please help? Thanks in advance!

[maxnoe]

For future reference: the issue was that the pre-commit hook wasn't yet installed for some of the commits.

To run it on all files affected by this PR, the solution was:

pre-commit run --files $(git diff --name-only origin/main)

[kosack]

We can generalize it more later, but for now this is fine

[maxnoe]

monitoring/extractor.py is a new module, it needs to be added to the API docs.

Please add it in docs/api-reference/monitoring/ .

You can check the other files there

[TjarkMiener]

Please add it in docs/api-reference/monitoring/ .

I tried to added following the structure of the other modules, but the docs are failing. Can you please have a look @maxnoe? Thanks in advance!

[maxnoe]

The error is not in the new docs page (these are fine!) but in the docstring of one of the new classes:

 /home/runner/work/ctapipe/ctapipe/src/ctapipe/monitoring/extractor.py:docstring of ctapipe.monitoring.extractor.StatisticsExtractor.__call__:4: WARNING: py:obj reference target not found: chunk_shift
/home/runner/work/ctapipe/ctapipe/src/ctapipe/monitoring/extractor.py:docstring of ctapipe.monitoring.extractor.StatisticsExtractor.__call__:4: WARNING: py:obj reference target not found: chunk_shift

which are now included in the docs, which is why you didn't see them before.

You need double back-ticks in rst for code:

``chunk_shift``