Auto-scale cells based on panel size

[Erog38]

I'd love to pitch (and potentially commit) the capability of scaling square cells based on the panel size so you don't have to scroll, but the cells would get bigger if you make the panel larger.

[KatrinaTurner]

Hi @Erog38! Sorry so late to the party, but if you'd like to submit a PR for this, I think it'd be a nice addition. I think it would be best to add it as an option to select "Auto" sizing as some people do like to set the size specifically themselves.

You'll want to work against the 2.0.1 branch as that is the one currently waiting for approval from Grafana