LOW-915: Low ITF tests incoming
This MR copies the Low ITF tests here from ska-low-itf-scripts.
A second commit autoformats the notebooks, and a third commit updates the linting toolchain: on the one hand, we add notebook linting to the CI toolchain; but on the other hand, ska-low-itf-scripts was overriding the notebook-lint make target to turn off pylint and flake8, and I've temporarily shipped that over here so that I don't have to fix a bazillion linting errors immediately.
(And a fourth commit to make Marvin a wee bit less shouty.)
Edited by Drew Devereux