Support for globs

Currently we have multiple GraphQL files in our source code and I need to run this for each file individually. It would be much more convenient if globs were supported. Then I could run something like:

```sh
npx format-graphql --write=true ./src/**/*.graphql
```

Start with the format-graphql CLI entry point and inspect how positional file paths are parsed. Support the ./src/**/*.graphql invocation so each matched GraphQL file is processed, including with --write=true, and verify the command formats all matched files.

Written by the indexing model from the issue text.