feat(http): meteor user ID in http handler

[jamiter]

This will make Meteor.userId work in resolvers when calling them from the HTTP endpoint.

• Why: userId with collection-hooks apollographql/meteor-integration#92 and Document how to call code that relies on server-side global Meteor.userId() apollographql/meteor-integration#16
• How: Feature Request: Enable this.setUserId in server-initiated methods meteor/meteor#6388

We recommend to never use it yourself. Use the userId from the passed context. But this helps to support a lot of Meteor packages out of the box which depend on Meteor.userId() to work.