feat(gatsby-plugin-typescript): allow specifying babel preset options (#10248)

* Pass through babel preset options

* Add options section to gatsby-plugin-typescript docs

* format

Author: colebemis

packages/gatsby-plugin-typescript/README.md

@@ -21,6 +21,28 @@ module.exports = {
 }
 ```
 
+## Options
+
+When adding this plugin to your `gatsby-config.js`, you can pass in options to override the default [@babel/preset-typescript](https://babeljs.io/docs/en/babel-preset-typescript#options) config.
+
+```javascript
+// gatsby-config.js
+module.exports = {
+  plugins: [
+    {
+      resolve: `gatsby-plugin-typescript`,
+      options: {
+        isTSX: true, // defaults to false
+        jsxPragma: `jsx`, // defaults to "React"
+        allExtensions: true, // defaults to false
+      },
+    },
+  ],
+}
+```
+
+For more detailed documentation on the available options, visit https://babeljs.io/docs/en/babel-preset-typescript#options.
+
 ## Caveats
 
 This plugin uses [`babel-plugin-transform-typescript`](https://babeljs.io/docs/en/babel-plugin-transform-typescript.html)

packages/gatsby-plugin-typescript/src/gatsby-node.js

@@ -1,8 +1,9 @@
 const resolvableExtensions = () => [`.ts`, `.tsx`]
 
-function onCreateBabelConfig({ actions }, pluginOptions) {
+function onCreateBabelConfig({ actions }, options) {
   actions.setBabelPreset({
     name: `@babel/preset-typescript`,
+    options,
   })
 }