Support for `@` in descriptions

[louy]

According to the docs, @ in description comments makes the comment get truncated

Depending upon your version of TypeScript, descriptions with a @ symbol in their text, for example a GitHub handle, may get truncated. To avoid this, you can wrap the tag in quotes or backticks.

/** This comment was added by `@captbaritone`. */

This limitation makes it impossible to put GraphQL example code in documentation comments.

For example, take the native @semanticNonNull that grats ships with. This is impossible to declare using grats:

import {Int} from 'grats';
/**
 * Indicates that a position is semantically non null: it is only null if there is a matching error in the `errors` array.
 * In all other cases, the position is non-null.
 *
 * Tools doing code generation may use this information to generate the position as non-null if field errors are handled out of band:
 *
 * ```graphql
 * type User {
 *     # email is semantically non-null and can be generated as non-null by error-handling clients.
 *     email: String @semanticNonNull
 * }
 * ```
 *
 * The `levels` argument indicates what levels are semantically non null in case of lists:
 *
 * ```graphql
 * type User {
 *     # friends is semantically non null
 *     friends: [User] @semanticNonNull # same as @semanticNonNull(levels: [0])
 *
 *     # every friends[k] is semantically non null
 *     friends: [User] @semanticNonNull(levels: [1])
 *
 *     # friends as well as every friends[k] is semantically non null
 *     friends: [User] @semanticNonNull(levels: [0, 1])
 * }
 * ```
 *
 * `levels` are zero indexed.
 * Passing a negative level or a level greater than the list dimension is an error.
 * @gqlDirective on FIELD_DEFINITION
 */
export function semanticNonNull({ levels = [0] }: { levels: Int[] }) {}

Produces a truncated description:

"""
Indicates that a position is semantically non null: it is only null if there is a matching error in the `errors` array.
In all other cases, the position is non-null.

Tools doing code generation may use this information to generate the position as non-null if field errors are handled out of band:

```graphql
type User {
    # email is semantically non-null and can be generated as non-null by error-handling clients.
    email: String
"""
directive @semanticNonNull(levels: [Int!]! = [0]) on FIELD_DEFINITION

Afaik there is currently no work around in grats to produce the desired output.

Playground reproduction.

[captbaritone]

It looks like TypeScript supports escaping @ with \@.

https://www.typescriptlang.org/play/?#code/PQKhCgAIUgJBTANog9pAOgAQC4At4BO8UMJkZJw42AngA7yQBiKaAvJAEQBCAhgZyA

I think Grats should try to do the same. Let me see if I can figure out how.

[captbaritone]

Next step here will be to poke through TypeScript code to see exactly where/how this happens to see if there's a public function we can reuse or if we can at least be sure we are matching their implementation.