feat: add notifier for download

haas-imagej-client/src/main/java/cz/it4i/fiji/haas/Job.java

...i/haas/data_transfer/PersitentSynchronizationProcess.java

...java/cz/it4i/fiji/haas/data_transfer/Synchronization.java

...in/java/cz/it4i/fiji/haas/ui/ObservableValueRegistry.java

...4i/fiji/haas_spim_benchmark/core/BenchmarkJobManager.java

.../fiji/haas_spim_benchmark/core/UpdatableBenchmarkJob.java

.../fiji/haas_spim_benchmark/ui/BenchmarkSPIMController.java

...aas_spim_benchmark/ui/ObservableBenchmarkJobRegistry.java

...nchmark/src/test/java/cz/it4i/fiji/haas/RunBenchmark.java