Set up mbgl-tile-renderer to run as a task worker service

[rudokemper]

Goal

To enable mbgl-tile-renderer to be run as a task worker service that can poll a queue for new requests. This PR adds support for Azure Storage Queue.

Screenshot

What I changed

• Add a new file azure_queue_service.js which works with Azure Storage Queue to process a queue message containing a JSON body with the expected values required for rendering.
• These values are passed to initiateRendering, which now takes an outputDir to be able to specify a volume mount in addition to the standard output/ dir. Currently, this is hard-coded as /maps which is the directory we are mounting on the Docker container in Azure.
• Once rendering has been completed, the tool deletes the queue message from the storage queue.

What I'm not doing here

• More work is needed on validations and throwing exceptions given this new deployment environment. That will come next.
• Integration work to update a Postgres db table upon completion.