Custom operation builder

[DamianCzajkowski]

This pull request merges the latest version of the custom operation builder into the main branch. This update includes foundational features necessary for building custom queries and mutations.

Features Included

• Initial implementation of the custom operation builder.
• Basic support for creating and managing custom queries and mutations.
• Initial tests and documentation for the feature.

Next Steps

Once this pull request is merged, a new issue will be created to outline further enhancements and improvements needed for this feature. These enhancements will include:

• Support for introspection fields.
• Support for directives.
• Support for query/mutation as a return type.
• The ability to select specific queries/mutations from the schema.

We look forward to collaborating with the community to refine and expand this feature. Contributions are welcome, and we appreciate your support in making this tool more robust and user-friendly.