Revert "protocol/charybdis: remove unneeded banforward stripping"

This reverts commit 11f4447c403505f516ccc4649b3c4017ede77367.

Charybdis in fact supports ban forwarding and needs this code to ensure
they are matched properly.
Revert "Require opers to use the FORCE option to view private channel flags"

This reverts commit 4ff8d13075d6f252a431eee6a4966115389d5aa3, reversing
changes made to bbb0a6329d6249d23e8e9456d27c24a2ba3a9bc2.

There's no need to require that opers specify force, as many other
commands that only show information don't require this kind of thing
either, which is desired behavior.