Add OVH Provider

[Hugome]

Not perfect, open to any comment/criticize, GO is not my main language.
(For example the little hack with json Marshal/Unmarshal on the mocked ovh client in test...)

This respond to #809 (And a personal need)

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[Hugome]

/assign @hjacobs

[njuettner]

thank you for adding a new provider 🙏, I added some comments PTAL.

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[Hugome]

Thanks for your notes :)
I've done some changes/comment, tell me if it's ok for you.
(Sorry for the CLA warning, it was the wrong git account...)

[njuettner]

@Hugome do you mind resolving the conflicts?

[Hugome]

@njuettner Yes no problem, done.

[njuettner]

@Hugome thanks for your effort integrating OVH as a provider 🙏. It slighty missed the current release but will be in the next one.

/lgtm

[njuettner]

/approve

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Hugome, njuettner

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