Improve program sensor

[frimtec]

Currently the sensor "program" shows a combination of two device states (Inactive and Program).
This leads to the following issues:

• For devices like the "Cooler V2000", the device value of program is mostly hidden with "standby" as the value "Inactive" is true in normal operation mode.
• For devices like the "Combair-Steamer V2000", the program shows "standby" even if the device is active (Inactive is false), but no specific program is selected.

The PR tries to address both issues:

• If the value of the device field "Program" is set, it has always priority.
• If the value of the device field "Program" is empty, depending on the device field "Inactive" the value "standby" or "active" is reported.

[siku2]

Awesome, thanks!