The `WE_ARE_TOXIC` state is added as a sanity check to ensure that if
the remote has proven that we have lost state we do not accidentally
do a local force-close. E.g. if we receive an "error" message for the
channel, we might normally do an automatic force-close. Manually
force-closing in such a state is not offered anymore by the GUI.
The `REQUESTED_FCLOSE` state is added as it is quite likely that
we receive an error message from the remote after requesting a fclose,
e.g. during a later chan-reestablish. In such a scenario, we should
not do an auto-local-fclose, however the manual option of a local-fclose
should still be offered.
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