Use std::chrono::duration types consistently

[CodingCanuck]

::eventuals::Timer() takes a std::chrono::milliseconds:

eventuals/eventuals/timer.h

Line 11 in d423018

[[nodiscard]] inline auto Timer(const std::chrono::milliseconds& milliseconds) {

But it's just a pass-through to Clock().Timer(), which instead takes a std::chrono::nanoseconds:

eventuals/eventuals/event-loop.h

Lines 1283 to 1284 in d423018

	[[nodiscard]] inline auto EventLoop::Clock::Timer(
	std::chrono::nanoseconds nanoseconds) {

We should standardize on one type type for timers.

We probably should also pass std::chrono::duration types by value, not const&: https://stackoverflow.com/questions/37918168/pass-stdchronoduration-by-value-or-by-reference-to-const since they're essentially backed by ~ints by default: https://en.cppreference.com/w/cpp/chrono/duration