This adds an "extraLabels" parameter to add labels to an internal helper
that maintains the labels for the various resources.

Also bumps the chart version accordingly.

This commit fixes a namespace selector in the Prometheus Operator's
ServiceMonitor definition. If you deploy the Helm release into, say, the
default namespace, but use a namespaceOverride to put Fluent Bit into
the "fluent-bit" or "cloudwatch" namespace, then this will look in the
wrong Kubernetes namespace for your service and you won't get metrics.

Custom labeling should be applied to the DaemonSet too, and this is
possible only if we use the full labels instead of just the
selectorLabels.