protect: Improve protection weighting logic

Previously, on a page with move=sysop alone, a request for
edit=autoconfirmed was considered a decrease in protection. However,
such a request should imply that the move=sysop is maintained, so we
need to consider each type of protection in isolation (edit/stabilize go
together) when deciding which section of RPP to post into.
Also adding FlaggedRevs/PC into the weighting scheme (see L680 comment).