Show more details about interface on hover

[normalser]

interface Interface {
    a: string
}

type Type = {
    a: string
}


// Hovering over `Interface` shows only `interface Interface`
let a:Interface

// Hovering over `Type` shows `Type = { a: string }`
let b:Type

[RyanCavanaugh]

In general interfaces are longer. For many types (e.g. Window) we'd end up showing an unreasonably large tooltip that would be unuseful.