fix(core): ComponentFixture autodetect should detect changes within A…

[atscott]

…pplicationRef.tick

The current behavior of autoDetect in ComponentFixture does not match production very well. It has several flaws that make it an insufficient change detection mechanism:

• It runs change detection for the component under test after views attached to the ApplicationRef. This can cause real behavior differences that break in production, because tests can observe view refreshes in the incorrect order (for example, a dialog refreshing before the component which opened it).
• Because of the above ordering, render hooks registered during change detection of the fixture views will not execute at all because ApplicationRef.tick already happen.
• It does not rerun change detection on the view tree if there are more dirty views to refresh after the render hooks complete.
• It effectively hides/swallows errors from change detection inside the onMicrotaskEmpty subscription by not reporting them to the error handler. Instead, this error ends up being unhandled in the subscription and rxjs throws these in a setTimeout.

All of the above are problematic but this commit does not fix the final point. Ideally, we can land this in a future change but this requires additional internal fixes. In the meantime, we have to juggle special-case handling of the component fixture views within ApplicationRef.tick using some special events to retain current behavior and avoid errors from the fixture propagating to the ErrorHandler.

BREAKING CHANGE: The ComponentFixture.autoDetect feature now executes change detection for the fixture within ApplicationRef.tick. This more closely matches the behavior of how a component would refresh in production. The order of component refresh in tests may be slightly affected as a result, especially when dealing with additional components attached to the application, such as dialogs. Tests sensitive to this type of change (such as screenshot tests) may need to be updated. Concretely, this change means that the component will refresh before additional views attached to ApplicationRef (i.e. dialog components). Prior to this change, the fixture component would refresh after other views attached to the application.

[atscott]

This PR was merged into the repository by commit 24bc0ed.

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