add a rule to capitalize named operations

[solomon23]

Adds a rule to check for capitalized named operations

TODO:

• Make sure all of the significant new logic is covered by tests
• Rebase your changes on master so that they can be merged easily
• Make sure all tests pass
• Update CHANGELOG.md with your change
• If this was a change that affects the external API, update the README

[apollo-cla]

@solomon23: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Apollo Contributor License Agreement here: https://contribute.apollographql.com/

[solomon23]

I’ve signed the document. Anything else needed here ?