Add typings

[matthieusieben]

I am currently using the following to type @hapi/nigel. 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.

// types.d.ts

declare module '@hapi/nigel' {
  import { Writable } from 'node:stream'

  export interface Haystack {
    readonly length: number
    readUInt8: (pos: number) => number | undefined
    startsWith?: (value: Buffer, pos?: number, length?: number) => boolean
  }

  export interface Needle {
    readonly value: Buffer
    readonly lastPos: number
    readonly last: number
    readonly length: number
    readonly badCharShift: Buffer
  }

  export function compile(needle: Buffer): Needle
  export function horspool(haystack: Haystack, needle: Needle | Buffer, start?: number): number
  export function all(haystack: Haystack, needle: Needle | Buffer, start?: number): number[]

  export class Stream extends Writable {
    constructor(needle: Buffer)
    needle(needle: Buffer): void
    flush(): void
  }
}