feat: Operation selection in gql requests

[nasdf]

Relevant issue(s)

Resolves #1395

Description

This PR allows multiple operations to be defined within a request and selected using an operationName param.

Tasks

• [x] I made sure the code is well commented, particularly hard-to-understand areas.
• [x] I made sure the repository-held documentation is changed accordingly.
• [x] I made sure the pull request title adheres to the conventional commit style (the subset used in the project can be found in tools/configs/chglog/config.yml).
• [x] I made sure to discuss its limitations such as threats to validity, vulnerability to mistake and misuse, robustness to invalidation of assumptions, resource requirements, ...

How has this been tested?

added tests

Specify the platform(s) on which this was tested:

• MacOS