Enforce naming convention for GraphQL files based on best practices

To adopt and enforce best practices when it comes to naming.

* Names must have the following cases:
```yaml
# ----------------------------------------
# Examples:
# ----------------------------------------
# alternatingcase("Hello, world!") --> "hElLo WoRlD"
# camelcase("Hello, world!") --> "helloWorld"
# cobolcase("Hello, world!") --> "HELLO-WORLD"
# flatcase("Hello, world!") --> "helloworld"
# kebabcase("Hello, world!") --> "hello-world"
# macrocase("Hello, world!") --> "HELLO_WORLD"
# pascalcase("Hello, world!")= "HelloWorld"
#
# For other alternatives, see: https://github.com/chrisdoherty4/python-case-converter
#
# ----------------------------------------
# GraphQL SDL default naming conventions
# ----------------------------------------
type:
name: pascalcase

interface:
name: pascalcase

enum:
name: pascalcase
value: macrocase

field:
name: camelcase
argument: camelcase

input
name: pascalcase

union:
name: pascalcase

scalar:
name: pascalcase
```
* If a field has an output type with a `List` modifier, then its name must be plural.
```gql
type Example {
passenger: [Person] # <-- This is wrong!
passengers: [Person] # <-- Correct
}
```

No file or test is named; search the repository for the GraphQL SDL parsing or validation entry point, using the issue's examples as cases. Done means the specified naming conventions and plural names for list-valued fields are enforced, with tests covering violations and accepted names.

Written by the indexing model from the issue text.