Bug: uni v3 adapter multi-hop whitelist skip

[gabririgo]

When a user uses a multihop route that involves a non-whitelisted token as the first route tokenOut, the transaction is reverted. This should not happen. Even if this involves routing through potentially rogue tokens, it entails a sophisticated attack by a rogue operator.

In the opposite case, a rogue trader could route through a whitelisted-tokenOut-pair first, to then purchase a non-whitelisted token. This defies the scope of the token whitelist, so we either fix it or we remove the token whitelist entirely. At that point, we should keep track of owned tokens in an indexed mapping.

The affected code part can be found here