For expired tokens without an `autoRenewAccount`, fallback to paying renewal fee with their treasury

### Problem

Suppose a user accidentally created an immutable token without an `autoRenewAccount`.

Once expiration is enabled, this could lead to some annoyance of the token users needing to manually extend its lifetime.

### Solution

Use a token's treasury as a fallback auto-renew account.

### Alternatives

_No response_

Start by locating the token expiration and renewal entry points and the existing handling for autoRenewAccount. Check how a token’s treasury is represented and how renewal fees are charged. Done means an expired token without autoRenewAccount can use its treasury for the renewal fee, with regression coverage for this fallback.

Written by the indexing model from the issue text.