Fix an issue with inaccessible Duck.ai fragment (#6850)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/1208671518894266/task/1211468322303343?focus=true

### Description

Fixes an issue with inaccessible Duck.ai fragment that could happen
after failed fragment state transaction.

If the Duck.ai close transition finished after `onSaveInstanceState`,
the fragment container would be hidden but the fragment itself wouldn't.
This led to an invalid state where the app thought the fragment was
visible, preventing it from ever re-launching, but its container was
`gone`.

To resolve the issue, this PR:
1. Allows for lossy fragment transaction when closing Duck.ai. This
resolves any potential crashes that
#6839 attempted to fix.
2. Checks for fragment and its container state consistency when trying
to open Duck.ai. This prevents any state locks in rare cases where
activity is restored from saved state after being in Duck.ai mode.

### Steps to test this PR

The issue was mostly reproducible for me in `release` variant and with
Input Screen enabled, because on New Tab Page the Input Screen reopens
after closing Duck.ai fragment which has a higher likelihood of
canceling the transitions.

- [x] Enable Input Screen.
- [x] Open New Tab Page.
- [x] Open Input Screen.
- [x] Send a prompt to Duck.ai.
- [x] Go back and reopen the Input Screen.
- [x] Send another prompt to Duck.ai and verify it correctly opens.

Author: LukasPaczos