* Decomposed tests into atomic unit tests
* Made tests less time-dependent, hence more robust
on different platforms (ESP32, QEMU, Linux)
* Ported most of the tests to linux
* Removed some redundant tests
* Fixed bug the tests discovered
* Simplified parts of the tests to be more clear
* Partially used C++ to simplify setup/teardown
* Unified setup/teardown in general
* improved setup/teardown to not put shared event system into
inconsistent state
* reduced timing-dependency of several tests by using
a semaphore instead of waiting for a guessed timeout
* Deactivated WDT (both Interrupt WDT, Task WDT) for QEMU tests
* Ignore esp_timer-based test for QEMU, CPU timing is different
on ESP32 simulation in QEMU
