Add Support for Azure WAL-G Backups (#1537)

This commit adds support for using an Azure storage account as a backup
location.

It uses the existing GCS functionality as a reference for what to do,
and follows the example set by GCS as closely as possible.

The decision to name the cloud provider key "aws_or_gcp" is unfortunate
while adding support for Azure, but I have left it alone to allow for
this changeset to be backwards compatible.

charts/postgres-operator/crds/operatorconfigurations.yaml

@@ -395,6 +395,8 @@ spec:
                     type: string
                   wal_s3_bucket:
                     type: string
+                  wal_az_storage_account:
+                    type: string
               logical_backup:
                 type: object
                 properties:

charts/postgres-operator/values.yaml

@@ -268,6 +268,9 @@ configAwsOrGcp:
   # GCS bucket to use for shipping WAL segments with WAL-E
   # wal_gs_bucket: ""
 
+  # Azure Storage Account to use for shipping WAL segments with WAL-G
+  # wal_az_storage_account: ""
+
 # configure K8s cron job managed by the operator
 configLogicalBackup:
   # image for pods of the logical backup job (example runs pg_dumpall)