#### Support "directives on directive definitions" (#19171 by @YBJ0000)

[Directives on directive definitions](https://github.com/graphql/graphql-js/pull/4521) (and `extend directive` extensions) are now supported.

<!-- prettier-ignore -->
```gql
# Input
directive @a @b on QUERY
extend directive @a @b

# Prettier stable
Error: Syntax Error: Expected "on", found "@".

# Prettier main
directive @a @b on QUERY
extend directive @a @b
```
