Add kiosk session duration UMA metrics

Kiosk session uptime is a good indicator of kiosk reliability.
Kiosks often run 24/7.
Add 4 UMA histograms:
* Kiosk.SessionDuration.Normal
* Kiosk.SessionDurationInDays.Normal
* Kiosk.SessionDuration.Crashed
* Kiosk.SessionDurationInDays.Crashed

Long sessions > 24h (1 day) are distinguished from the short ones and
logged as 1 day session ones. Also the cap for the long session duration
is 100 days (if the session is longer than 100 days, they are capped
with that value).

BUG=b:214364560
TEST=./unit_tests --gtest_filter="AppSessionTest*"
TEST=start kiosk session on dut, reboot/restart/pkill -9 browser several times \
     check Local State for kiosk-metrics

Change-Id: If817255072ad85abcd0bcf7574029dc5629e5a7d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3599052


Reviewed-by: Edman Anjos <edman@chromium.org>
Commit-Queue: Polina Bondarenko <pbond@chromium.org>
Reviewed-by: Andrey Zaytsev <andzaytsev@google.com>
Cr-Commit-Position: refs/heads/main@{#999814}