There is one thing that this PR doesn't fix, that I had hoped it would.

Although it allows you to choose your own subnets for each item, it doesn't allow you to define a single subnet for Web, Redis, San, Tika, Elastic (AppGW and Vnet GW always need their own). This would be useful for testing scenarios, scenarios where your segregation is taken care of via a Virtual Firewall, or scenarios where you are restricted on subnets

I welcome any feedback on how to achieve this part.

Going to pull this one back as I did some work later that improved this a lot.