[todo-mvvm-live-kotlin] Espresso idle counter gets corrupted

In todo-mvvm-live-kotlin in Util/ViewExt.kt, in the callback of the showSnackbar function there gets the EspressoIdlingResource incremented and decremented.
The problem is, that if onDismissed is called before onShown, the counter gets corrupted.
This case may happen if showSnackbar is called two times in a really short period of time.

Start in todo-mvvm-live-kotlin/Util/ViewExt.kt at the showSnackbar callback and trace how EspressoIdlingResource is incremented and decremented. Reproduce two rapid showSnackbar calls, including onDismissed before onShown, and verify that the idle counter remains balanced in both callback orders.

Written by the indexing model from the issue text.