Run observers before hooks for on_replace and on_remove

[nakedible]

Objective

• Fixes Hook and observer ordering for on_remove/on_replace should be inverted #16498

Solution

• Trivially swaps ordering of hooks and observers for all call sites where they are triggered for on_replace or on_remove

Testing

• Just CI

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Migration Guide

The order of hooks and observers for on_replace and on_remove has been swapped. Observers are now run before hooks. This is a more natural ordering where the removal ordering is inverted compared to the insertion ordering.

[bushrat011899]

This makes sense to me conceptually. Nice work!

[nakedible]

The fix pull runs now hooks after observers, but observers are run in the same order as on insertion, not in reverse order. Flecs says observer ordering is undefined, and I also think that having undefined ordering is better than saying observers are called in insertion order (or reverse insertion order). So I believe it's fine that the observers are not run in reverse order by this pull.

[nakedible]

If guaranteed observer ordering is added (in a separate pull), then that pull should also add functionality to call the observers in reverse order, and this reverse order should be used for OnReplace and OnRemove observers.