Make it possible to watch all namespaces from non kube-system namespace

[wilmardo]

Currently deploying the operator in another namespace then kube-system implicitly disallows global watching: https://github.com/Altinity/clickhouse-operator/blob/aaee541b6d2b1ae79aa2d11088ec9c7f377a1dc3/pkg/apis/clickhouse.altinity.com/v1/type_config.go#L323-L329

It would be nice to have a parameter for this behavior, we deploy all operators in the operator namespace and they are cluster global.

I am open to implement this but what is a nice approach to this? A WATCH_ALL_NAMESPACES boolean? When WATCH_NAMESPACES or WATCH_NAMESPACE is defined it will be ignored.

PS why not consolidate WATCH_NAMESPACE and WATCH_NAMESPACES into just WATCH_NAMESPACES? Nothing wrong with a list with one entry or am I missing something? Feels weird as enduser :)

[anxolerd]

I'd also like to have operator installed in its own namespace, but watching all namespaces.

By the way, I've heard, it is common practice for users of operator-framework to watch all namespaces if WATCH_NAMESPACE environment variable is empty.

[TCeason]

I'd also like to have operator installed in its own namespace, but watching all namespaces.

By the way, I've heard, it is common practice for users of operator-framework to watch all namespaces if WATCH_NAMESPACE environment variable is empty.

If set empty just only watch the ns where operator was installed.

https://github.com/Altinity/clickhouse-operator/issues/686