Rework science code to use interrupts

[tabiosg]

The current architecture of the science code is a round robin w/ interrupts. In the round robin (the loop) is code to read from the thermistors and the spectral sensors. This loop currently takes quite a while to run (about a full second per loop) because reading takes a long time.

A good issue for (new) members next year to tackle is figuring out how to make this faster by either messing around with the hardware (e.g. what registers we're reading from and if it's an issue because of i2c/adc read transaction settings) or changing the software architecture (e.g. move spectral code into interrupts instead).

For reference, here is the link to the code for the loop that takes long to run: https://github.com/umrover/embedded-testbench/blob/official_science/science_nucleo_g0/Core/Src/main_loop.c#L18

[qhdwight]

I don't know enough about this particular system but in general you want to use interrupts. Any blocking operation should be avoided.