esp32: Deactivate wakeup trigger after first wakeup
The files updated according to code review discussions.
In the sleep_modes.c removed immidiate disable of ULP mode and leave just trigger deactivation.
The esp_sleep.h is updated to have the same defines for source as esp_sleep_wakeup_cause_t.
Updated documentation in sleep_modes.rst file to include cross references and address esp_sleep_wakeup_cause_t type.
Some minor changes in test_sleep.c unit test.