Issue 7383 - Split out core io-filter-list functionality

One of the features that make the io-filter-list component unique, is its ability to render an "infinite" amount of items, in our case all filters, something completely unrelated to the layout that the table, or any of its rows, will have.

In order to reuse such functionality for https://gitlab.com/eyeo/adblockplus/abpui/adblockplusui/issues/129, I'm proposing this little refactoring that takes out everything that is not render centric, so that I can compose any other kind of table on top (i.e. io-filter-language-list).