Switch Azure deployment to Kubernetes

[c-w]

Previously we were hosting the ok-server, ok-worker, autopy-manager and
autopy-worker in AppService for containers. However, we were seeing some
issues with this approach as workers were killed without death
notifications and rq/Redis was getting confused. After this change, we
now deploy the compute (workers and servers) to Azure Kubernetes
service.

In order to make it easier to orchestrate the setup of the various
resources in Azure as well as the Kubernetes deployments, we're using
bash scripts. First, we create a bunch of resources using setup.sh and
then we configure them using install.sh. The setup scripts are wrapped
in a Docker container so that the environment in which the scripts
execute is well known, e.g. Azure CLI is installed, helm is available,
kubectl is available, etc.

Most of the setup scripts fall-back to ARM templates to create the
resources in Azure. The ARM templates can be modified to configure
parameters such as resource SKUs, number of VMs to spin up for the
cluster, type of VMs to use in the cluster, etc.

The install scripts perform operations such as creating the database
schema, deploying the application to Kubernetes via Helm and setting up
the DNS for the Kubernetes ingress via the Azure CLI so that kube-lego
can configure a TLS certificate for the ingress via Let's Encrypt.

Note that the ingress to the applications running in the Kubernetes
cluster are configured as just one entrypoint so that a single TLS
certificate and DNS entry can be used (Azure public IP resource
currently only support a single DNS label per IP). To solve routing, we
thus need to mount the two sub-applications (OKpy and AutoPY) at
sub-urls of the ingress which requires some minor application changes
which are submitted in a separate pull request:
#1300

The setup scripts can be run either via the "Deploy to Azure" button (in
which case the setup Docker container is run in an Azure Container
Instance) or via a local docker run command. In the latter case, it's
advised to also include a volume mount docker run -v $PWD:/app/secrets
so that the access keys for the resources created during the deployment
will be made available to the deployer. Note that in order to skip
deploying specific resources (e.g. to re-use existing resources), you
can place a file into the secrets folder that contains the access keys
for your existing resources in which case the setup scripts will skip
deploying that step.

[colinschoen]

Happy to merge this... here is the stamp. I'll let you merge in case you want someone else from Microsoft to review.

[c-w]

@marrobi @martinpeck Would you like to review this or are you happy to merge this as-is? There's an architecture diagram here:

[c-w]

@colinschoen Let's merge this. Thanks!