Add Support for Zapier

[ideadude]

We'd like to e.g. trigger an action in Zapier when a user is approved, unapproved, or denied.

We can build a system that could be polled from Zapier similar to the native integration in PMPro.

Or maybe we rely on the PMPro Zapier Add On and create a new "trigger" there that pushes to Zapier.

Let's collect thoughts here on how this could be done and specifically what the use cases are we want to address.

[dwanjuki]

A customer was asking if it's possible to trigger a Zap on membership approval Mods: 631942