How can I create a stopwatch with Rx in Kotlinv with Observables, so anything can subscribe to it:
- It shall remain even when I put the app in background
- I start the Observable with anything I configure: 9000 [ms], 600 [s], etc.
- It counts down to 0 in its unit [ms], [s], etc.
- When reached 0, either fires an event or delivers default 0 [unit]
