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.
The get_time_ms() is updated to explicitly use fabs(dt) instead of abs(dt) in test_sleep.c.
Some other minor changes in test_sleep.c unit test.
(TW#18952)
Closes https://github.com/espressif/esp-idf/issues/1677
cffab50ac3