GraphQLSchema does not completely validate names

The validateName function that is used to validate lots of schema parts is currently only checking that names are not reserved: https://github.com/graphql/graphql-js/blob/6b253e7159a6a6c64c05bcc6bb863fef5a42eeb7/src/type/validate.ts#L206-L217 It should also check that the name complies with https://spec.graphql.org/October2021/#Name, e.g. by testing against the regex /^(?!__)[A-Za-z_][A-Za-z0-9_]*$/. Otherwise it's possible to construct schemas (via the constructor, not by parsing) that upon printing would lead to invalid syntax, or fields which could never be queried. (Not the case, see below)