GraphQL and HTTP client improvements

[stayallive]

• Set api_target on GraphQL request bodies to graphql to allow Sentry to highlight it nicely

  

  Since we are not technically doing a HTTP client request but we are the GraphQL server I have not included the response since we have never done that in PHP yet. And since I couldn't find any docs on the GraphQL server thingies I tried this (2d35c89) and it looks very nice but not a 100% confident it is "correct".

• Add missing response_body_size and request_body_size to HTTP client breadcrumbs (https://develop.sentry.dev/sdk/features/#http-client-integrations)

[cleptric]

@stayallive Want to move this forward? We can follow up on response handling and errors in another PR.

[stayallive]

I'm pretty happy with this 👍

[smeubank]

do we need docs changes for PHP for this?

[cleptric]

As we talked about during our daily, there are no changes needed in a user's application to enable the improved GrapQL request payload highlighting.
GraphQL errors are not part of this PR. This might come as a follow-up.