fix(graphql): using nested resolvers in @graphql resolver

[meskill]

Summary:
Briefly describe the changes made in this PR.

Issue Reference(s):
Fixes #... (Replace "..." with the issue number)

Build & Testing:

• [ ] I ran cargo test successfully.
• [ ] I have run ./lint.sh --mode=fix to fix all linting issues raised by ./lint.sh --mode=check.

Checklist:

• [ ] I have added relevant unit & integration tests.
• [ ] I have updated the documentation accordingly.
• [ ] I have performed a self-review of my code.
• [ ] PR follows the naming convention of <type>(<optional scope>): <title>

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 93.02326% with 3 lines in your changes missing coverage. Please review.

Project coverage is 86.22%. Comparing base (dd41d6a) to head (a8c5f54).

Files	Patch %	Lines
src/core/blueprint/operators/graphql.rs	86.36%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2235 +/- ## ======================================= Coverage 86.21% 86.22% ======================================= Files 212 213 +1 Lines 20427 20456 +29 ======================================= + Hits 17612 17638 +26 - Misses 2815 2818 +3 ```

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