Build filtering for Experiment results

[jurajmajerik]

Feature request

Is your feature request related to a problem?

Our users currently create dashboards to be able to filter various things when viewing experiment results.

As a workaround to having limited secondary metrics, we have been creating dashboards for each experiment/feature flag that requires more in depth analysis and tracking. This means we can use the full suite of metrics/visualizations and all of the filters/breakdowns and put them together on a dash to monitor performance. It would be great to have something like that, where you can choose the metrics and then toggle between different views (e.g. timeseries, cumulative), time periods, see breakdowns by key dimensions, apply filters to everything, etc.

More context: https://posthog.slack.com/archives/C06KJQ2RH1A/p1731548474319069?thread_ts=1730850089.425729&cid=C06KJQ2RH1A

Describe the solution you'd like

We should either:

• Embed this filtering functionality within the Experiment results view
• Add the ability to auto-create a dashboard with all experiment metrics

Describe alternatives you've considered

Additional context

Debug info

- [ ] PostHog Cloud, Debug information: [please copy/paste from https://us.posthog.com/settings/project-details#variables]
- [ ] PostHog Hobby self-hosted with `docker compose`, version/commit: [please provide]
- [ ] PostHog self-hosted with Kubernetes (deprecated, see [`Sunsetting Kubernetes support`](https://posthog.com/blog/sunsetting-helm-support-posthog)), version/commit: [please provide]