this makes the graphql peer dependency required. While the hope is to eventually avoid the need to
require the graphql library for users who don't declare graphql requests directly, the current
architecture means that many tools fails to properly compile without error/warning without this.

Since NPM 7, npm will automatically install peer dependencies, which should avoid consumers of msw
having to manually install graphql.

re mswjs#1371

removes the previous attempt at making graphql optional by lazily requiring it instead of importing
it.  This didn't have the intended affect of helping to avoid parsing in many environments, and
might be confusing and/or cause friction with a future migration to using native modules and
providing an export that can be treeshaken in all environments.

re mswjs#1371