Let's move Scrapy-related code from the Actor template to here as @fnesveda pointed out here apify/actor-templates#223 (review) and also on Slack.

I'm starting to think that we should put (most of) the Apify <-> Scrapy logic into some package, either some new one (apify-scrapy-utils) or into the Apify SDK. Right now, with the logic in the template or wrapper, once a user creates a Scrapy Actor, they're stuck with whatever was in the template or wrapper at time of creation. If there was a bug in the logic (or some future version of Scrapy brings some incompatibility), we have no real way of fixing it in existing Actors. If we had the logic in a package, we could just instruct the users to update that package to fix the issues. Plus we wouldn't have to maintain the logic in both wrapper and template.