Utilise existing funnels as goals when creating experiments.

[jonmcwest]

Feature request

Is your feature request related to a problem? NO

Describe the solution you'd like

We've already got funnels set up in our product analytics suite. We often want to run tests that affect these funnels. It would save time and increase stability when setting the goal for an experiment, to select a pre-existing funnel.

Currently, we have to re-create the funnel, which is time consuming and prone to error.

Describe alternatives you've considered

N/A