Web Analytics: Add better UI for choosing which actions / events are shown in the Goals query

[robbie-c]

Feature request

Is your feature request related to a problem?

In the Goals query, we show the actions sorted by pinned_at and created_at. This is not obvious, and doesn't provide much flexibility.

Describe the solution you'd like

It'd be great if I could search for / choose actions and custom events to appear instead.

Describe alternatives you've considered

Keep as is.
Make these changes but don't include custom events.
Make these changes and allow clicking on goals to set them as the global conversion goal