Update namespace v2 (#465)

* Revert "Revert "feat: Ability to create custom labels for namespaces created … (#455)"

This reverts commit ce2fb703a6a7b5e0b5e8ee3e1f1b34747dcec844.

Signed-off-by: Blake Pettersson <blake.pettersson@gmail.com>

* feat: enable namespace to be updated

Rename `WithNamespaceCreation` to `WithNamespaceModifier`, since this
method is also used for modifying existing namespaces. This method
takes a single argument for the actual updating, and unless this method
gets invoked by its caller no updating will take place (fulfilling what
the `createNamespace` argument used to do).

Within `autoCreateNamespace`, everywhere where we previously added tasks
we'll now need to check whether the namespace should be created (or
modified), which is now delegated to the `appendNsTask` and
`appendFailedNsTask` methods.

Signed-off-by: Blake Pettersson <blake.pettersson@gmail.com>

Signed-off-by: Blake Pettersson <blake.pettersson@gmail.com>