Add the Ability to log multiple POTA references

[magicbug]

Discussed in https://github.com/magicbug/Cloudlog/discussions/3096

^{Originally posted by nolith May 5, 2024} POTA has the 2-fer, 3-fer location where a QSO is valid on multiple references. This is also supported by the ADIF spec but I was not able to mark a single QSO with more than one POTA reference. Am I doing something wrong or this is a missing feature?