[Feature Request] Charge state Determination for sparse spectra

[ZimmerD]

Is your feature request related to a problem? Please describe.
The current implementation of the charge state determination does yield an empty list when only the monoisotpic peak is detected.
Describe the solution you'd like
Since no charge inference is possible the result should not be an empty list but a list with all possible charge states so that the correct one can be assigned by psm.