Various improvements to transect capability

[James W (jwarner8)]

Broad collection of improvements to the transect capability in CSET, addressing the following issues/enhancement requests:

• Producing an infographic/inset showing location of transect [Plot infographic plots for transect and verification plots #830]
• Callback to fix varname from ML models that prevents colorbar from being fixed.
• Support aggregation options for transect.
• Allow multiple transects to be specified in GUI.

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• Documentation has been updated to reflect change.
• New code has tests, and affected old tests have been updated.
• All tests and CI checks pass.
• Ensured the pull request title is descriptive.
• Ensure rose-suite.conf.example has been updated if new diagnostic added.
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[github-actions]

[James W (jwarner8)]

Status 26/03
Modifications to transects have now been made

Started plumbing the aggregation side of things, need to debug why all models are being loaded for one model aggregation. It seems to load model 1 and 2, i.e. the parbaked recipe looks like

file_paths:

• ~/cylc-run/cset_workflow/run11/share/cycle/*/data/1
• ~/cylc-run/cset_workflow/run11/share/cycle/*/data/2

this leads to

Constraint doesn't produce single cube: ConstraintCombination(ConstraintCombination(ConstraintCombination(Constraint(), Constraint(cube_func=<function generate_cell_methods_constraint.<locals>.check_no_aggregation at 0x148eceefaae0>), <built-in function and_>), Constraint(name='x_wind'), <built-in function and_>), Constraint(coord_values={'pressure': <function generate_level_constraint.<locals>.<lambda> at 0x148eceefac40>}), <built-in function and_>)
0: x_wind / (m s-1) (time: 16; pressure: 28; latitude: 186; longitude: 142)
1: x_wind / (m s-1) (time: 16; pressure: 28; latitude: 186; longitude: 142)
2: x_wind / (m s-1) (time: 8; pressure: 13; latitude: 281; longitude: 321)
3: x_wind / (m s-1) (time: 8; pressure: 13; latitude: 281; longitude: 321)

A separate problem here is that cubes don't merge in a given model, but primary issue here is two models being loaded. Need to determine if other aggregation recipes do the same.