Support for event attribute filtering on funnel steps

If your feature has an onboarding funnel, you can now filter on event attributes when creating funnel steps. This enables you to track the funnel sliced by a certain attribute value - like browser, feature version or any other custom attribute - or to use just one event for all the funnel steps.

In the example below, the funnel onboarding steps use an event called `messaging_setup` which then has an attribute called `funnelStep: [1,2,3…]` for each step of the funnel.

More updates soon!