Add Azure storage support to dtool

Features

To install the dtool-azure package:

pip install dtool-azure

Install the Azure command line client via:

pip install azure-cli

(you may wish to install this in a virtual environment)

Then:

az login

To log into Azure.

Then you need to run (changing the resource name/group as appropriate):

az storage account show-connection-string --name jicinformatics --resource-group jic_informatics_resources_ukwest

Then create the file .config/dtool/dtool.json and add the Azure account name and key using the format below:

{
    "DTOOL_AZURE_ACCOUNT_KEY_<ACCOUNT NAME>": "<KEY HERE>"
}

Changing the account name and key as appropriate. For example if the account name was "jicinformatics" and the key "some-secret-token":

{
    "DTOOL_AZURE_ACCOUNT_KEY_jicinformatics": "some-secret-token"
}

To copy a dataset from local disk (my-dataset) to an Azure storage account (jicinformatics) one can use the command below:

dtool copy ./my-dataset azure://jicinformatics/

To list all the datasets in an Azure storage account one can use the command below:

dtool ls azure://jicinformatics/

See the dtool documentation for more detail.