feat(ferry_exec): Pass context to GQL Links

[tpucci]

• feat: pass context to gql links
• feat: update generated code

Generated code was updated with "void" statements. I am not sure why

Feature request: #575

In order to create advanced Links that can execute custom logic per request, we need a way to extend request with ContextEntries.

Currently, generated code for a request is:

  @override
  Request get execRequest => Request(
    operation: operation,
    variables: vars.toJson(),
    // no passed context. Thus, the default is `context = const Context()`
  );

gql_exec has a method .withContextEntry on Operation that we could use.

I'd be happy to contribute if you think it is a good issue 🙂

(😅 Hope I did not miss something in the API that already allows us to create context entries) Reference: #556

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[tpucci]

I'd be happy to fix verify_commits but I did not understand why it failed

[knaeckeKami]

It was the name of the PR. edited it for you and reran the action :)

(this is so CHANGELOGs can be created automatically with melos)

[knaeckeKami]

LGTM!