Introduce non-interruptive Phase events

As discussed with Charles, and previous comments, we should have two categories of phase events :
- interruptive
- non-interruptive

By interruptive we mean that the phase event happens after all tests have finished. The next phase will be a new execution of the suite.

Today we only have interruptive events.

What we would like to introduce is a way of executing phased tests where the phase event is within the test suite itself.

By default this should be the property of the test environment.

This may mean that we introduce a new phase: ProCon

When selected we will expect a phase event to be executed within the project.

We may then have to introduce scenario events.

No files, tests, or entry points are named. Start by reviewing the existing interruptive phase-event behavior and the prior discussion, then clarify how non-interruptive, ProCon, and scenario events should work. Done should be defined as an agreed implementation scope with tests covering the two event categories.

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