Allow disabling Posthog from helm

[Nastaliss]

Feature Request

I'd like to disable the Posthog url forwarding by default, as I do not (yet) use this service and would like to make the setup process as straightforward as possible.

Describe the solution you'd like
Add a .Values.posthog.enabled key to the value.yaml file and set it to true by default, this way no breaking change is introduced.
Disable the k8s resources if set to false

Describe alternatives you've considered
/

Discovery, Documentation, Adoption, Migration Strategy
Update the readme accordingly

Do you want to work on it through a Pull Request?
#1013

[Nastaliss]

Just realized that setting both ingress.enabled and ingressAssets.enabled to false will have the same effect.
It was not clear that disabling ingress would also disable the svc (and therefore disable the whole component).