Add optional graphqlClientIntegration to @sentry/browser

[mydea]

Description

Similar to getsentry/sentry-cocoa#3931, we can add a pluggable (=not enabled by default) integration to @sentry/browser (and downstream SDKs) which allows to opt-in to get better breadcrumbs & spans when using GraphQL as a client.

This could behave like this:

Sentry.init({
  integrations: [
    Sentry.graphqlClientIntegration({
      endpoints: ['/graphql'],  
    })
  ]
})

Where any http.client span or breadcrumb created that matches endpoints will be enhanced with graphql data from the request payload:

1. For http.client spans, we can update the span name similar to what we do here in node: feat(node): Add useOperationNameForRootSpan tographqlIntegration #13248
2. For breadcrumbs, we can add the operation name to the breadcrumb data (and possibly also the query itself)

related: #13215

[andreiborza]

Leaving this here for future reference: #13215 (comment)