Change copyright to GraphQL Contributors, License to MIT

[acao]

@leebyron @caniszczyk this should be it. Creating this PR in the official graphiql instead of the fork this time so it's part of the PR history

[acao]

@caniszczyk can you review this today so we can merge the ide monorepo at the WG tomorrow?

[IvanGoncharov]

@acao In graphql-js, I just removed copyright headers see: graphql/graphql-js#1960
Here is motivation for doing that: graphql/graphql-js#1960 (comment)
I think would be great to do the same here to have consistency in all graphql/* projects.
What do you think?

[acao]

@IvanGoncharov I agree that this makes sense. I did this in a previous PR, but then @caniszczyk asked me to re-introduce the headers with a different copyright message.

[IvanGoncharov]

I did this in a previous PR, but then @caniszczyk asked me to re-introduce the headers with a different copyright message.

@acao Totally makes sense in this case. Thanks for sharing context around this decision.

[acao]

@caniszczyk can you give this a review so we can merge for the WG meeting today?

[caniszczyk]

LGTM

[acao]

thank you!