Copy exporter attribute instead of modifying parent class

[daradib]

Fixes #104.

[macv-hub]

It seems this change has been reverted so the problem still persists for jupyter notebook and jupyter lab where the default class attribute HTMLHideInputExporter.exclude_input.default_value is set to True and therefore the parent class attribute. In my humble opinion, making a copy of the attribute made sense to avoid the same behaviour using different exporters. However, I feel the real issue is with VScode where the exporter doesn't show the 'no input' options when exporting.

I include this image to illustrate the behaviour without copy command:

It appears that handcalcs.exporters.py doesn't add the functionality intended to vscode. Not sure if this can be configured within the IDE rather than hardcoded. Another issue is that any other jupyter notebooks are also not showing any input even when handcalcs is not imported. Does anyone get the same?