Exceptions with $important modifier in uBO filter lists are invalid

[superlex]

Unlike AdGuard, in uBO $important modifier applies only to network block filters: https://github.com/gorhill/uBlock/wiki/Static-filter-syntax#important

FiltersCompiler should ignore them or remove $important modifier from these rules, otherwise they will be considered invalid.

Example: @@||connectivitycheck.gstatic.com^$important from https://filters.adtidy.org/extension/ublock/filters/2_without_easylist.txt