fix(core): make parent injector argument required in `createEnvironmentInjector` by AndrewKushnir · Pull Request #46397 · angular/angular

…ntInjector`

Previously, the `createEnvironmentInjector` function allowed creating an instance of an EnvironmentInjector without providing a parent injector. This resulted in an injector instance, which was detached from the DI tree, thus having limited value. This commit updates the types of the `createEnvironmentInjector` function to make the parent injector a required argument.