restructure the repo into docker/ and k8s/

[konstan]

With the coming support of NE on k8s-based edge the suggestion is to create separate folders per supported COE.

@schaubl Can you please update the list of the things to be checked

• automated install,
• NE release retrieval job for Nuvla,
• NE installer container used for updated (related https://github.com/SixSq/tasklist/issues/2125)
• all previous versions are still working after we change something.

It's based on our exchange outside of GH.

... is dangerous and will probably break couple of things because some workflows expect some files to be in 
some specific places in this repo (for example, automated install, NE release retrieval job for Nuvla, NE installer 
container used for updated and others operations, etc)

With the NE we need to be careful because we need to make sure all previous versions are still working after 
we change something.