Add `display` as a traitlet in `SPEalgorithm` component

[pcorcam]

Please describe the use case that requires this feature.
Needed to run (subclasses of) the FlatFieldSPENominalNectarCAMCalibrationTool when defining the option to display plots using traitlets.config.

Describe the solution you'd like
Right now, display is passed as a kwarg to the SPEalgorithm component; see also user_scripts/ggrolleron/gain_SPEfit_computation.py. I suggest to define display as a configurable trait of the SPEalgorithm component. That way, we can also pass this option as e.g. config["FlatFieldSPENominalNectarCAMCalibrationTool"].display = False.

Additional context
Note that SPEalgorithm already contains a method with the name display, so need to be careful with names.

[jlenain]

Hi @guillaumegrolleron !

This request comes from the need to be able to enable/disable the generation of plots on the local disk when chaining components for the computation of Cat. A/B calibration coefficients by @pcorcam (see #226).

If you agree, I can take care of a PR to make this small change.
What do you think ?

[guillaumegrolleron]

Hi @jlenain and @pcorcam,
I definitely agree, it's a good improvement to make the display configurable with a trait !

[jlenain]

Thanks.

To avoid shadowing the method SPEnominalalgorithm.display, I'd propose to name this field display_toggle.

[jlenain]

@pcorcam , would #228 work ?

[pcorcam]

@jlenain, yes #228 looks perfect! Thanks!