Use fenced code blocks in TSDoc `@example` tags

**Is your feature request related to a problem? Please describe.**

Our generated code currently contains TSDoc `@example` tags with unfenced source code, for example:

````ts
/**
* __useCartQuery__
*
* @example
* const { data, loading, error } = useCartQuery({
* variables: {
* sellerId: // value for 'sellerId'
* },
* });
*/
````

**Describe the solution you'd like**

These should be fenced code blocks per the docs (https://tsdoc.org/pages/tags/example/), like this:

````ts
/**
* __useCartQuery__
*
* @example
* ```ts
* const { data, loading, error } = useCartQuery({
* variables: {
* sellerId: // value for 'sellerId'
* },
* });
* ```
*/
````

**Describe alternatives you've considered**

Leaving it the way it is, but this confuses `prettier-plugin-jsdoc`, which we use to format our files. Because of this, our examples are broken.