Overriding SchemaPrinter to bypass check on Subscriptions.

In Webonyx, the getType() function can return null. In GraphQLite, it throws an error.
This makes using the SchemaPrinter impossible.
We override the SchemaPrinter to stop searching for the "Subscription" type.

Note: this can only work if webonyx/graphql-php#1380 is merged.

Addig a graphqlite:export-schema command

This new Laravel command can be run using

```
./artisan graphqlite:export-schema --output file.schema
```

It will output the content of the Schema to an SDL file.
This can be useful for instance for tools like graphql-codegen.

Merge pull request #43 from thecodingmachine/http_code_decider

Adding an option to set HttpCodeDecider

Merge pull request #42 from thecodingmachine/laravel-9-and-10

Adding compatibility with Laravel 9 and 10

Merge pull request #35 from vuongxuongminh/patch-1

fix: `debug` setting in graphqlite config file

Merge pull request #41 from bmangeat/fix/disable-test-php-8-1

fix/disable-test-php-8-1

Merge pull request #34 from DenisVinokurov/master

Add support thecodingmachine/graphqlite 5

Merge pull request #30 from tamellal/master

fix-new-UploadMiddleware-class-bug

Merge pull request #26 from Alejinho/master

Add support for Laravel 8.x

Merge pull request #24 from moufmouf/upgrade_laravel7

Adding Laravel 7 compatibility