Add azure cli completion

[Riezebos]

I haven't created a zsh completion before, I used the _aws file as a starting point and updated it based on https://stackoverflow.com/a/49277309. Tried it out and seems to work.

[Riezebos]

Update: I saw that the azure-cli repo now has a different way to register completions, I tested it and it worked and seemed maybe a bit faster. Source: https://github.com/Azure/azure-cli/blob/dev/src/azure-cli/az.completion.sh