Fixed typings to be compatible with express

[ehrencrona]

A more conservative version of #1710 that fixes #1706.

There seem to be three issues with the request:

• the search property that's supposed to hold the query string doesn't actually exist. No idea how it wound up in there. It's also not referenced anywhere in the code so easy to remove.
• query can contain a wider range of stuff than SapperRequest declares. I grabbed the Express definition but we could also do Record<string, any>
• socket assumed it was always an https connection

This seems to compile with both Polka and Express when I tested it

[ehrencrona]

Come to think of it, #1710 is the better solution. I vaguely remember that the request interfaces were different between Polka and Express, which is the only reason there should be a SapperRequest in the first place. If the Express typings work (either that has changed or I was wrong), then it's better to just use them directly.

[benmccann]

I actually like yours better. I'll reopen this until we figure out which one to merge

[dummdidumm]

I like this one better as well, but take this opinion with a grain of salt as I don't know much of Sapper's typings. What I like more about this is that this one is more self-contained.