Add PowerShell script to start Docker stack

This commit adds a PowerShell script that mirrors the existing `deploy_stack.*` scripts.

It also checks that docker is installed and returns a readable error if not found (the alternative is a rather cryptic PowerShell error).

The docker stack command itself returns a readable error if no swarm has been initialised.

Signed-off-by: John McCabe <john@johnmccabe.net>

deploy_stack.ps1

@@ -0,0 +1,11 @@
+#!ps1
+
+if (Get-Command docker -errorAction SilentlyContinue)
+{
+    Write-Host "Deploying stack"
+    docker stack deploy func --compose-file ./docker-compose.yml
+}
+else
+{
+    Write-Host "Unable to find docker command, please install Docker (https://www.docker.com/) and retry"
+}