Training: Patch Size input - enforce value of x, y, and z to be multiples of 4

### Problem
Currently we mention that the patch size value for x, y, and z must be multiples of 4 in the guide text below the "Patch size" label and also in its tooltip. However, we can take one step further to code enforce the input

### Acceptance criteria
When user inputs values into the x, y, and z fields, the values are checked to be multiples of 4, if not, get to the closest value that satisfies this requirement