Grafana renderer

[amnonh]

The grafana renderer is an extension that allows a user to download capture of a dashboard.
When I tested it, it run very slow, so I'm not sure how useful it will be.

This series adds it as an optional, by running start-all.sh with -E.

Fixes #904

[amnonh]

@fruch I'm adding it as an option, can you take it for a spin?

[fruch]

@fruch I'm adding it as an option, can you take it for a spin?

I can confirm it's working, and taking ~30sec for a full dashboard, it's a lot, spining up chrome with webdriver take much more time then that (when it works)

[bentsi]

@amnonh are you planning to include this in the next Scylla Monitoring release?

[tzach]

@amnonh we need to move away from startup options to cloud oriented work.
Scylla Cloud users can not control these option, so we need to decide if we want to include it or not.

[fruch]

@tzach, I think it's o.k. to gather some feedback first, then we see it's working good, enable it by default.

[roydahan]

I agree with @fruch.
And yes, 30s is long but better than what we have now.