When a publishing uses a publish prefix, instead of listing the contents
of the whole bucket under the storage prefix, only list the contents of
the bucket under the storage prefix and publish prefix, and cache it by
publish prefix.
This speeds up publish operations under a prefix.
This adds a new configuration setting: AzurePublishEndpoints, similar
to the existing S3PublishEndpoints and SwiftPublishEndpoints.
For each endpoint, the following has to be defined:
- accountName
- accountKey
- container
- prefix
Azure tests require the following environment variables to be set:
- AZURE_STORAGE_ACCOUNT
- AZURE_STORAGE_ACCESS_KEY
With either of these not set, Azure-specific tests are skipped.