Add GraphQL Inspector to project

[MorganFH]

Is your feature request related to a problem?

Currently, breaking changes can be introduced to the GraphQL schema and go unnoticed. In general, any changes made to the schema can be subtle to identify and it is challenging to ensure they do not cause any errors.

Describe the solution you'd like

We should add GraphQL Inspector to the project (e.g. introduce github actions for PRs and perhaps install the CLI as well). See their introduction page for a brief overview.

Describe alternatives you've considered

Additional context