Add typings

I am currently using the following to type `@hapi/vise`. It would be nice if this module exported its own types. I d'ont have the time or resources to make a PR. Sorry about that.

```ts
// types.d.ts

declare module '@hapi/vise' {
export class Vise {
readonly length: number
push(bhunk: Buffer): void
readUInt8(pos: number): undefined | number
at(pos: number): undefined | number
chunks(): Buffer[]
shift(length: number): Buffer[]
startsWith(value: Buffer, pos?: number, length?: number): boolean
}
}

```