Unsupport $collapse filter option

Background

The $~collapse filter option disables element collapsing (i.e. causes the blocked element to not be hidden). For the most recent past there has been only a single filter in EasyList using that option, and we won't be able to keep supporting that option with manifest v3 anyway.

What to change

Remove support for the $collapse filter option.

Integration notes

• Remove the check for filter.collapse from platform::lib/requestBlocker.js::port.on('filter.collapse')
• Existing filters with the $collapse/$~collapse option need to drop the option in order to function

Hints for testers

• Test that $collapse options flag as a filter is invalid
• Test that a filter with the $collapse option enabled does not have side effects on the rest of the list, e.g. given two filters ||example.com/foo/bar^$~collapse and ||example.com/foo^, the second filter should still block requests to http://example.com/foo/bar