sesutil: Add extra information specific to some SES devices to sesutil map

Rework stat2ascii preparing a buffer of what could be printed. This prevent the
risk of overflowing a static buffer.

Do not print those informations anymore in the "status" but into a new
"extra status" only printed if there are actually extra things to print.

Now add those extra informations:

• Thermal sensor temperature
• Cooling devices speed
• Voltage sensors, current consumption

Tested by: AllanJude
Sponsored by: Gandi.net
Differential Revision: https://reviews.freebsd.org/D4520