Support Clear Linux

[vholer]

Add support for Clear Linux contextualization with official package and Marketplace image.

Please, place emoji on this initial comment in case you are interested in this feature. It allows us to track the level of interest. Thank you.

[hpcchris]

👍

[hpcchris]

This might be a good place to mention that Clear Linux has gotten some attention in the high performance computing, machine learning and edge computing areas- it seems to be a somewhat niche distro at present, but a contextualization package might drive traffic to the OpenNebula platform. Thanks for all your hard work.