Gutter icons would be more effective than inline discussions

[nicksnyder]

Inline discussions are functionally just a link to the full discussion, but they need to be toggled on first and I don't find them to be visually appealing.

I think it would be better if "inline discussions" were removed and there was just a persistent gutter icon (ideally on by default) for existing discussions on the file. Would greatly help discoverability of existing discussions and would not disrupt the code reading experience.

[emidoots]

• Sourcegraph Extensions cannot insert gutter icons, so we cannot do this. https://github.com/sourcegraph/sourcegraph-extension-api/issues/68
• We also cannot improve the visual appeal of them either due to having no information about the color scheme: https://github.com/sourcegraph/sourcegraph-extension-api/issues/63