Polar data manager

[scyrock]

Currently, polar data are managed separately by polarstack.py and routingwizarddialog.py. This separation can lead to data inconsistencies and increased complexity. Additionally, the ability to import external polars (e.g., #173, #160) should be handled within a unified framework to ensure consistency and simplify management.

The introduction of a polar manager similar to gribmanager.py may solve it.

[dakk]

Good idea; we can extend storage, so we are able tò save Polar settigs (enabled state)