feat: support port 443/TLS connections for grafana service

[ericpaulsen]

the grafana service is provisioned solely with port 80 exposed. our customers will expect to access this over HTTPS, so we'll need a grafana.service.tls.enabled value (or something to the effect).

[ericpaulsen]

i can write this in, i just don't know where the service template is defined in the chart.