Feature flags in toolbar frontend

[rcmarron]

Changes

The front-end work to allow users to override their feature flags from the toolbar.

Dependent on #5824

feature-flag-demo.mov

Remaining items todo:

• Tests
• Get Posthog feature flags flowing into the toolbar to turn this feature on and off (super meta 🤔)

Checklist

• All querysets/queries filter by Organization, by Team, and by User
• Django backend tests
• Jest frontend tests
• Cypress end-to-end tests
• Migrations are safe to run at scale (e.g. PostHog Cloud) – present proof if not obvious
• New/changed UI is decent on smartphones (viewport width around 360px)

[rcmarron]

This is ready for review. A couple of notes:

• This feature lives behind the feature flag posthog-toolbar-feature-flags, and can only be rolled out internally right now. This is because toolbar does not have access to Posthog's feature flags. Rather, the toolbar has access to the customer's feature flags, so right now, this feature will only work internally (because in that case, the "customer" is Posthog and we have the flag posthog-toolbar-feature-flags set). There is a bit of work to give the toolbar access to feature flags, and when we want to roll this out, we can either do that work or just remove the feature flag that it's behind.
• The toolbar can definitely use a design pass beyond this feature. I tried to make the existing panels match the styles for the new feature flag panel, but it was a bit tricky. (see the pics below for where I landed) @clarkus I'd love your thoughts here.

• Here is a quick demo of the feature

feature-flag-override-demo.mov

[clarkus]

@rcmarron This looks good to me. I am tracking longer term toolbar improvements at #2370. If you had any specific items you think should be addressed, can you add them to that issue?

[mariusandra]

This looks amazing!

I have just two comments regarding the nemesis of all macOS frontend developers: scrollbars 🤣 .

1. The actions view has a scrollbar:
   

I actually recommend everyone working in frontend enable this setting to always catch them:

The problem is all Windows computers always show scrollbars, so it'll look really ugly for those users... and we must prevent that.

2. The scrollbar here is also slightly off. Could it be at the very right of the window?