Show temperature progress bar when changing temperature

[seb-cap]

After setting temperature, show bar with how close to selected temperature the actual temperature is

[ojf]

FYI, the current software shows if we're at the set-point by changing the background color of a box next to the temperature display: https://github.com/UWMRO/ScienceCamera/wiki/Reference-Guide#set-temperature

Just a suggestion, but this acts like a warning light if the camera isn't at temp, which is a potentially simpler/nicer feature than a bar.