Release Req: Replace Help button

[Jayclifford345]

It has been requested that we replace the question mark within Grafana:

Rather than install our own icon:

I believe this will be a little more involved than we hope it will be:

1. Understand how the current help icon is integrated and if there is functionality in place for us to replace it. We may have to contribute to Grafana/Grafana
2. The help button comes with its own set of features, such as a series of navigation buttons. We now provide these within our plugin, but we need to make sure we support the white labelling of the documentation button for a user's own docs
3. Remove the current book icon from grafana/grafana once we have a working version of above
4. Make sure we add the button replacement functionality to our feature flag in OSS