Call image stream listeners asynchronously if added asynchronously (#95525)

* Call image stream listeners with new flag

* Make _synchronousCall private

* Rename _synchronousCall parameter to be more descriptive and add more documentation

* Rename _hasInitialListeners to _addingInitialListeners and provide a better explanation

* Formatting fix

* Add tests

* Remove dependency on decoration_test.dart

* Simplify tests

* Remove empty line in comment

* Documentation

* Trigger tests

* Trigger tests

* Flip boolean value