Remove import statement from CSS modules feature

[foolip]

Fixes #1164.

[captainbrosset]

As posted here #1164 (comment), ensuring that we use BCD keys just once in the repo feels like an arbitrary limitation that will become a problem for us at some point.

Not opposed to making this quick change to fix MDN, and javascript.statements.import.import_attributes.type_css does mean that javascript.statements.import is supported anyway, so I will approve. But I wish we had a long term solution in place that didn't involve making BCD keys unique throughout the repo.

[foolip]

@captainbrosset I've filed #1173 and will go ahead and link that with a TODO here instead.