Resolve "Task constructor API change"

Closes #43

See merge request workflow/est!44

Move Process to Ewoks `Task` and update setup

See merge request workflow/est!40

- complete signature to be `run`
- fix test
- orangecontrib: make inheritance to `Registered` instead of `OWEwoksWidget`
Because `OWEwoksWidget` enforce to use the defined ewokstaskclass which is not something we want for now (avoid task associated with gui, processes on threads...)

[converter oarnge table to XasObject]: fix issue with shape. Was probably not handling spectra with nelements.

- for now tests fails with larch but this come from larch (issue at the workfonw parametrization)