Adapted policies_logging.cpp tests to correctly handle statemachine start

[devzeb]

Problem:

While testing some logging behaviors, I noticed that the tests for logging were disabled in cmake.
The tests did not correctly handle the current implementation of sml_impl::start (sml.hpp, line 1501).

  template <class TDeps, class TSubs>
  constexpr void start(TDeps &deps, TSubs &subs) {
    process_event(on_entry<_, initial>{}, deps, subs);
  }

This code causes the sm to process the initial on_entry event, which then correctly invokes the logger for that event.
However, the test file policies_logging.cpp did not consider the log message of that initial entry event and therefore failed.

Solution:

• added log messages of the initial on_entry event to the vector of expected message
• re-enabled the tests in cmake

[kris-jusiak]

Thank you @devzeb