Improve KeyboardInterrupt handling.

[andreidenissov-cog]

In many cases throughout the code, we catch and handle BaseException in some manner.
Problem is, KeyboardInterrupt is a BaseException and so, it's handling somewhere along
a call stack effectively disables Ctrl-C during console application execution.
We need to make sure that KeyboardInterrupt always propagates to the top of call stack
to be handled by Python runtime and terminates execution fast.