drivers: sensor: st: add driver for the STM32 Digital Temperature Sensor

This add basic support for the STM32 Digital Temperature Sensor found
notably on the STM32H7 series. It work in interrupt mode and support
basic power device management.

It does not support the more advanced features like using the
temperature threshold, triggers from LPTIM or using the LSE clock in
during sleep or stop.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>