Ensure assertion success/failure is reported in EventMonitor

[azawlocki]

Summary of changes

Ensure that assertion success or failure is logged by an event monitor.

Description copied from the docstring in a unit test case added in 9b96799:

Test that assertion success and failure are logged.

This used to be a problem for assertions that do not succeed or fail
immediately after consuming an event. For example if an assertion
contains `asyncio.wait_for()` then it may raise an exception some time
after it consumed any event. After the failure, the monitor will not
feed new events to the assertion. But it should report the failure
(exactly once).

Add optional list of extra_monitors to Runner.check_assertion_errors()

This would simplify checking errors in monitors created ad hoc, not associated with a probe or an agent.
For example, one yapapi integration test ends with:

        for a in monitor.failed:
            raise a.result()

(https://github.com/golemfactory/yapapi/blob/d33d676081a7a29c30b695bb13f7b88c89bc9a46/tests/goth/test_resubscription.py#L190-L191).
After this change, one would be able to write instead:

        runner.check_assertion_errors(monitor)

Add colors to "Running test ..." and "Test finished ..." messages

A bonus. See e.g. https://github.com/golemfactory/goth/runs/2398454134?check_suite_focus=true#step:9:17 and https://github.com/golemfactory/goth/runs/2398454134?check_suite_focus=true#step:9:110.

[kmazurek]

👍