[essimaging]: Create a unit test that publishes a normalized image

[nvaytet]

Analysis team would like to have access to a normalized image that they can pick up to run nightly integration tests.

We need to create a unit test that publishes a reduced data file: a normalized image as Scitiff format.
It should be uploaded as a artifact. We can use the same mechanism as the output_folder fixture used in reflectometry or diffraction.

We can use the data from thr Bragg edge McStas experiment:

• use directly the correct flight path
• compute wavelengths
• normalize by open beam
• save as scitiff

Tagging @damskii9992