The state of the injector.
Describes the current state of the injector.
Inject or remove custom UI components based on the value of state.
If the value is InjectionState.mounting, then the injector has been mounted into the DOM.
If the value is InjectionState.unmounting, then the injector is about to be removed from the DOM. Any cleanup needed for custom components should be called here to prevent memory leaks.
For an example, refer to InjectionManager.