chore: add types for the configuration

[forivall]

This defines types for the config file, which can help when modifying the config file, as you can use a jsdoc type annotation to define the type and get some editor hints for the configuration options.

jest-mongodb-config.js

/** @type {import('@shelf/jest-mongodb').Config} */
module.exports = {
  mongodbMemoryServerOptions: {
    binary: {
      version: '4.0.3',
      skipMD5: true,
    },
    autoStart: false,
    instance: {},
  },
};