[CollapsingToolbarLayout] Consuming system window insets blocks sibling views from receiving insets

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**Description:**
CollapsingToolbarLayout is listening to window insets and inside the listener calls:
```java
// Consume the insets. This is done so that child views with fitSystemWindows=true do not
// get the default padding functionality from View
return insets.consumeSystemWindowInsets();
```
While consuming the insets, so its children do not receive them makes sense, due to how insets are dispatched by system, this causes insets to not be dispatched also to its sibling views.

Maybe it could only consume the insets only if `android:fitsSystemWindows="true"`?

After quite some trial & error I discovered a workaround: if I set my own insets listener (doing nothing) on the CollapsingToolbarLayout, I can avoid it consuming the insets. But this feels like hacking around it instead of proper solution.

**Expected behavior:**
System window insets are also dispatched to its sibling views.

**Source code:**
```xml

```

```kotlin
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
ViewCompat.setOnApplyWindowInsetsListener(recyclerView) { _, insets ->
// this will not be called
insets
}

ViewCompat.setOnApplyWindowInsetsListener(appBar) { _, insets ->
// this is called ok
insets
}
}
```

**Android API version:**
I checked on api 29.

**Material Library version:**
1.1.0, 1.2.0-alpha06

Start at CollapsingToolbarLayout's window-insets listener and reproduce the provided CoordinatorLayout with the RecyclerView sibling on API 29. Check that consuming insets for CollapsingToolbarLayout no longer prevents the sibling from receiving them, and add or update coverage if the project provides a relevant test entry point.

Written by the indexing model from the issue text.