Move supported drivers per platform

[josedonizetti]

This is something minishift do and is pretty useful. Wdyt?

[minikube-bot]

Can one of the admins verify this patch?

[k8s-ci-robot]

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[afbjorklund]

To be honest I'm not sure why even bother with plugins, if we are hard-coding the list of "supported" ones anyway ? It's not like you can add your own, since `minikube' will just complain that it is not supported...

But since we are going the way of validating the drivers (#4720), then maybe this makes the code prettier/smaller. And first glance it just looks like duplication, but maybe that can be cleaned up a bit ?

[josedonizetti]

@afbjorklund I don't see it the same way. I understood this supported drivers as something for the documentation, maybe the naming isn't good, but it is simple to change. I think the documentation should be as clean as possible, listing the KVM driver for a Windows user when he runs minikube start --help is misleading, and the idea here is to improve this documentation, not to force the use of only those drivers. That's the case for the PR #4720 as well, it should only validate that if someone tries the none driver in Darwin or Windows he is alerted this won't work, cos it's not for those environments, not that only those drivers are now supported and no one can try to create his own using a plugin.

At the same time, no strong feeling about all this we can close both PRs. :)

[afbjorklund]

I’m all for filtering out the invalid drivers (i.e. not available on platform)

[tstromberg]

@minikube-bot OK to test

[blueelvis]

Pretty sure Parallels is not supported on Windows.

[afbjorklund]

Apparently it got cancelled. https://www.parallels.com/blogs/parallels-desktop-for-windows/