Long scans: Noise removal algorithm

For gda that setup was with the long scan queue - but we do it with a plan. We need a plan that checks transmission chambers i0 and iT and takes a logarithm of the difference. That is the value on y axis. the x axis is different energies. we run 10 scans and each covers the whole energy range. We get 10 y values per each x point.

Y values are now raw in hdf, they are at the moment computed in dawn(?). while they could be in bluesky plans. the plan should take a parameter that is the expected noise level.

## Acceptance criteria

There is a bluesky plan tested on a beamline doing the above.