Add persistent storage implementation for Shoot clusters

[invidian]

How to categorize this issue?

/area storage
/kind enhancement
/priority normal
/platform equinix-metal

What would you like to be added:

Extension should optionally provide an implementation to provider persistence to Shoot clusters, which should utilize EM devices disks. Previously, there was Packet CSI, however it has been removed in #103.

Why is this needed:

In order to use "shooted seeds" functionality on EM, Shoot clusters must have storage available. Other Gardener extensions like AWS, GCP or Azure supports storage out of the box, so should we.

[gardener-ci-robot]

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/lifecycle stale

[gardener-robot]

@gardener-ci-robot Command /add is not available to you but only to a Maintainer, Member, Author.

[deitch]

/remove-lifecycle stale

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@deitch Command /remove-lifecycle is not known.

[deitch]

/remove-lifecycle stale

[gardener-robot]

@deitch Command /remove-lifecycle is not known.

[deitch]

@invidian @rfranzke is there an issue with the bot? I used the command it recommended and yet it says it does not know it.