Gathers and caches reflection data for the internal job system's managed bindings.
Unity is responsible for calling this method: don't call it yourself. When the Jobs package is included in the project, Unity generates code to call EarlyJobInit at startup. This results in the following benefits:
Note: While the Jobs package code generator handles this automatically for all closed job types, you must register those with generic arguments (like IJob<MyJobType<T>>) manually for each specialization with Unity.Jobs.RegisterGenericJobTypeAttribute.