support easier scaling of funktions + flows

[jstrachan]

right now when we modify a Function or Flow the operator updates the Deployment. So if you update the Deployment - for example to scale it - the replicas usually gets overwritten by the operator.

It'd be nice to make a fix to this though. e.g. maybe the operator preserves the replicas on the Deployment whenever its updating due to changes to the Function or Flow?

e.g. we want to be able to reuse auto scaling in kubernetes - so the operator shouldn't get in the way