#### Support "executable descriptions" (#18214 by @fisker)

<!-- prettier-ignore -->
```gql
# Input
"Description"
query {
  node {
    id
  }
}

# Prettier stable
SyntaxError: Syntax Error: Unexpected description, descriptions are supported only on type definitions. (1:1)
> 1 | "Description"
    | ^
  2 | query {
  3 |   node {
  4 |     id

# Prettier main
"Description"
query {
  node {
    id
  }
}
```