added new exponential noise implementation

[behinger]

No description provided.

[behinger]

what I dont yet like:
-> The default dropoff of 1000 should actually depend on the sampling rate, but it cant, becaue we are agnotistc to the samplig rate. So either we should provide a generator with sampling rate which interanlly reparameterizes tau to from time to samples, or we should not provide a default. Else the noise properties change drastically when changing sampling frequency

[jschepers]

@behinger Did you also have a look at the Reference docs page about Noise types? If everything fits for the new implementation.
And I guess the hint on the bottom of the page, needs to be adapted, right?
https://unfoldtoolbox.github.io/UnfoldSim.jl/previews/PR129/generated/reference/noisetypes/

[behinger]

• fixed the hint
• the size vs. length I changed because sometimes you don't want to have noise that 's "linearizeable", but rather produce it per event/subject whatever. prod(tuple) just calculates length out of the size-tuple

[jschepers]

I think the second point is not about this PR but one of the others.

[jschepers]

@behinger The label for ExponentialNoise in the Noise reference page needs fixing.

[jschepers]

@behinger The label for ExponentialNoise in the Noise reference page needs fixing.

I fixed it.