=act #13970 Send transistion on goto(CurrentState) in FSM

When in `A`:
* `goto(A)` will trigger `onTransition(A -> A)`
* `stay()` will NOT trigger `onTransition`

Includes:
* migration guide
* docs updates
* test
Merge pull request #15561 from ktoso/master

=act #13970 Send transistion on goto(CurrentState) in FSM