Build a new data collection calculator

[jurajmajerik]

Feature request

Is your feature request related to a problem?

The current data collection calculator has several issues:

• It produces different outputs for Trends vs Funnels (running time vs sample size), which is confusing.
• It assumes a 14-day period for event counts, and this cannot be adjusted.
• The only input it accepts is the Minimum Detectable Effect (MDE).
• It is too prominent in the UI, even though its use is optional and does not impact results.
• It hooks into dataLogic for its calculations, which makes it difficult to debug and understand.

Describe the solution you'd like

The ideal calculator would:

• Be well-integrated into the UI, with its purpose clearly explained.
• Allow multiple inputs, such as MDE and expected event counts (while we can give suggestions based on past data).
• Provide the same output regardless of the metric type.

Describe alternatives you've considered

Additional context

Related issues

• Configure relative/absolute MDE #21922
• Having the option to defining experiment success in terms of relative improvement & confidence interval #21928

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]

[danielbachhuber]

@jurajmajerik FYI - I linked to a couple of related issues in the description ^

https://posthoghelp.zendesk.com/agent/tickets/22108 is a related ticket.