feat(azure): add support for Storage File Shares

[aliscott]

This adds support for Azure File Shares. There's some overlap with azurerm_storage_account when account_kind = FileStorage, but I think that's okay since there's more flexibility with what they can do with azure_storage_share and we shouldn't break backwards compatibility. Everything can be adjusted with the usage file to make sure one resource get the cost.

There's also some overlapping logic with this and azurerm_storage_account but I decided to keep it separate for just now - unpicking the azurerm_storage_account resource was getting a bit messy.