fixup! Lox integration

Bug 42489: Require a loxId argument for most methods.

This ensures that a method only works on the credentials of the
*expected* loxId, rather than the newest `TorSettings.bridges.lox_id`
value which may change during a session.

We also add `#activeLoxId` to stay in sync with
`TorSettings.brigdes.lox_id`. We merge `clearInvites` into its updater.