Use GZRS for Storage Account by default

[bb-froggy]

The price is very low in all cases and the additional availability is nice.

[bb-froggy]

We must detect whether GZRS is available in the selected region and switch to ZRS or LRS if not

[bb-froggy]

Bicep seemingly provides no function to check which SKU is available in a given region. Furthermore, it seems there is no fallback mechanism if a SKU is not available.

We can maintain a list of regions where GZRS is available, synchronized from here: https://learn.microsoft.com/en-us/azure/storage/common/redundancy-regions-gzrs . They probably won't remove regions, only add new ones, so this shouldn't result in deployment failures.

If GZRS is not available, possibly we can still go for ZRS if the region is in this list: https://learn.microsoft.com/en-us/azure/storage/common/redundancy-regions-zrs

If this is also not available, we use LRS.