renderedCallback fires inconsistently after disconnect+reconnect in native lifecycle

[nolanlawson]

In native lifecycle, if you have a list of components using for:each, and the list is reordered (which causes LWC to remove+reconnect a list item), you get the following result:

1. renderedCallback fires for the list item component
2. renderedCallback does not fire for any children of the list item component

<template for:each={items} for:item="item">
  <x-item-wrapper key={item}></x-item-wrapper> <!-- fires renderedCallback -->
    #shadow-root
      <x-item></x-item> <!-- does NOT fire renderedCallback -->
</template>

Repro: nolanlawson@0c7dff5

It feels like we should either 1) consistently fire renderedCallback or 2) consistently not fire renderedCallback in this case.

In synthetic lifecycle, neither renderedCallback nor connectedCallback nor disconnectedCallback would fire after list reordering.

Note: this also applies to manually calling removeChild+appendChild, not just for:each. But it's most commonly seen in for:each.