AzureBlobStorage.UploadBlob - add support for folders inside the container

[RikuVirtanen]

Task can't handle nested containers inside the container name parameter if CreateContainerIfItDoesNotExist parameter is enabled. The Task uses await container.CreateIfNotExistsAsync(PublicAccessType.None, null, null, cancellationToken) with the complete string set in the container name parameter and if the container name is e.g. "test/container/01", the method can't find the container at all and the Task will fail even when the container exists. The Task needs to be able to handle nested containers with that parameter enabled.

[jefim]

I have spoken to Riku and we came to this:

1. We need to validate the container name parameter for it not to include slashes ( \ and / ). Throw an error to user if those are in the container name.
2. We need to add a new parameter to destination: TargetFolder. This then should be prepended to the blob names when we upload those. This will enable us to create those directories.
3. In the source parameters we need to rename two parameters for clarity:

• BlobName should become RenameToBlobName
• BlobFolderName should become RenameToFolderName

4. This is a breaking change, so bump the major version.