Rewrite numerical animation visualization to tool in utils/

[AlexanderMath]

The following lines of code construct the following visualization of numerics during a DFT calculation.

Line 1181
Line 137

Tasks
1 write a file pyscf-ipu/utils/visualize_numerics.py and import this into nanoDFT.py to be run if the user specifies --visualize_numerics True (don't change code in density_functional_theory.py
2 the above visualization defaults to run in float64. we want a mode which runs in float64 and float32 and (?somehow?) visualizes the difference between the two runs.