Add binder for notebooks

[lakhotiaharshit]

Add binder (mybinder.org) for the qcodes notebooks so that they can easily executed. Helps users to quickly interact with new features, APIs, and tutorials.

DRAFT because I am still playing around with the binder to look for the best settings

[jenshnielsen]

I don't know the best way to do this it may very whell be sphinx gallery but I would probably have tried something like https://github.com/spatialaudio/nbsphinx/blob/master/doc/conf.py#L39 which should render like the header in this notebook https://nbsphinx.readthedocs.io/en/0.5.1/configuring-kernels.html

[codecov]

Codecov Report

Merging #1943 into master will not change coverage.
The diff coverage is n/a.

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  Coverage   68.92%   68.92%           
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  Hits        13734    13734           
  Misses       6192     6192