Export location of express built-in middlewares

So I'm working to land https://github.com/expressjs/express/pull/3708 in the 4.17 branch now and I thought that `express.raw()` seems like a strange name, which made me think that handing the middlewares right off the `express` export itself is maybe weird?

I was thinking maybe we could put them under like `.middleware` or, if not, corral the parsers under `.bodyParser` maybe.

The following are the current middlewares:

- `express.json`
- `express.urlencoded`
- `express.static`
- `express.query`

The following are the 4.17 proposed middlewares:

- `express.raw`
- `express.text`

So I was thinking we maybe could do

1. `express.middleware.static` etc.
2. `express.static` and `express.bodyParser.json`, etc.
3. keep as-is

Maybe something else, even.

@LinusU @wesleytodd do you have any thoughts? This wouldn't block `express.raw` unless there was a general agreement like `express.middleware.raw` or something and the new ones could be landed under the new name up front and the rest moved instead of moving them all later, idk.