[grafana-operator] Support configuration of the Grafana application deployment

[rbs4ba]

Is your feature request related to a problem? Please describe.
Currently there is no support for controlling any of the configuration for the Grafana application deployment.

Describe the solution you'd like to see
It would be nice to have these configs exposed in the grafana.yaml template: https://github.com/banzaicloud/banzai-charts/blob/master/grafana-operator/templates/grafana.yam

https://github.com/banzaicloud/banzai-charts/blob/master/grafana-operator/crds/grafana.yaml#L100-L126
https://github.com/integr8ly/grafana-operator/blob/master/documentation/deploy_grafana.md#configuring-the-deployment

Describe alternatives you've considered
The config already exists at the operator level. But we could work around this by creating our own deployment, separate from the Grafana Operator install.