Evaluate the reasons for removal of the Trigger module from core.

Trigger was removed from core for D8 without providing a worthy alternative other than Rules (which by many is considered a "cumbersome piece of code with a confusing UI"). Having in mind our goals to be providing as much backwards compatibility as possible and easier transition from D7 to Backdrop, should we consider bringing trigger.module back in Backdrop core ...or at least putting it in contrib as a "lightweight" alternative to Rules (which is not fully ported yet and might take time to do so)?

For the record, here's a summary of the reasons for it's removal from D8 core (from the respective issue in the d.org issue queue: Remove Trigger module from core [#764558]):

The actions API is wonky (look up your action via hash of function name?), actions/trigger has no maintainer in MAINTAINERS.txt and we have not seen the promised conversion of things like node operations into actions.

Also, the trigger UI is weak, and there's not a lot you can do with it.

In general, people use a contrib module like Rules - so let's just put this code back in contrib where it belongs and reduce some of the bloat in core.