Feature/filter widget registry

[abmajith]

```bash EWOKS_WIDGET_FILTER="Ewoks Demo" ewoks-canvas EWOKS_WIDGET_FILTER="None" ewoks-canvas ```

select the required data processing group box (left side of the orange canvas), to limit the number of data processing groups

[codecov]

Codecov Report

❌ Patch coverage is 10.52632% with 17 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/ewoksorange/gui/canvas/main.py	10.52%	17 Missing ⚠️

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