Log temperature during OTA update

Log the maximum temperature as well as the start/end temperature of an
update to last_install. Check the temperature at the end of each
block_image_update(verify). To get the maximum temp, we iterate through
/sys/class/thermal/thermal_zone*/temp and find the maximum value
present.

Bug: 32518487
Test: temperature logs in last_install
Change-Id: Iaf22a9fbc5b18611bbc5320ffea995417872e514