Add algorithm SaveSavuTomoConfig (save savu tomography reconstruction pipeline config)

[FedeMPouzols]

This addresses ticket #10766, and is a sibling of PR #286.

This algorithm saves a table workspace with 'tomography reconstruction pipeline' configuration/settings data into a file in the format used by the savu tool (https://github.com/DiamondLightSource/Savu).

Tester:

• Review code.
• The algorithm comes with a unit test and a doc test, make sure that those are fine.
• You can also test it manually/interactively. With this (or similar to the doc test) you can generate a table as needed in the input to this algorithm:

t=CreateEmptyTableWorkspace()
t.addColumn("str", "ID")
t.addColumn("str", "Parameters")
t.addColumn("str", "Name")
t.addColumn("str", "Cite")

t.addRow(['save.plugin1', '{"silly param": 3}', 'Pipeline step 1', 'No cite'])
t.addRow([ 'save.median_filter', '{x: 0}', 'Pipeline plugin 2',  'Cite 2'])

The algorithm writes NeXus files like the example process??.nxs files found from here https://github.com/DiamondLightSource/Savu/tree/master/test_data.