Add period slice functions

[psanchez0046]

No description provided.

[jokasimr]

Thanks for the PR! Let's talk tomorrow about what the public interface of this functionality should look like.

Spontaneously I'm thinking something along these lines:

@dataclass
class SignalParameters:
    period: sc.Variable
    phase: sc.Variable
    

def estimate_signal_phase_and_period(signal: DataArray, method: Literal['fit] | Literal['fft'] = 'fit') -> SignalParameters:
    '''Lets the user estimate the parameters they need to associate events to a period slice.'''
    ...


def associate_events_to_period_slice(events: DataArray, signal_parameters: SignalParameters, period_slices: int) -> DataArray:
    '''Adds the period slice index, or the phase of the center of the period slice, as a coord on the event data.'''
    ...

This is very much a suggestion, so don't feel this is the only possible option.

Other than

1. estimating parameters from the signal, and
2. associating events to their period slice

what other functionality should there be in this module?

Maybe some sort of helper for visualizing the quality of the signal fit?