Optional chaining support for Gatsby's Babel config

Description

It enables the optional chaining operator (a ?. b): see the TC39 proposal

How to install

Install the plugin and its dependencies :

``bash
npm i @bumped-inc/gatsby-plugin-optional-chaining @babel/core @babel/plugin-proposal-optional-chaining
`

or

`bash
yarn add @bumped-inc/gatsby-plugin-optional-chaining @babel/core @babel/plugin-proposal-optional-chaining
`

Add the plugin in gatsby-config.js:

`js
module.exports = {
plugins: [
// other plugins
'@bumped-inc/gatsby-plugin-optional-chaining',
],
}
`

Examples of usage

`js
const maybeObj = null;
const result = maybeObj?.value; // result: undefined

const actualObj = { value: 5 };
const betterResult = actualObj?.value // betterResult: 5
``