Support mounting all disks

[RiRa12621]

How to categorize this issue?

/area storage
/area os
/kind enhancement

What would you like to be added:
A way to mount all existing disks

Why is this needed:
Certain non-cloud-provider resources have pre-defined configurations for nodes, which include multiple disks. An example for this is Equinix. When spawning an instance, for example m3.large.x86 comes with 2x 240GB SSD 2x 3.8TB NVME and as is with the spec below, gardener is only able to use the first volume, so 240g.

    workers:
      - cri:
          name: containerd
        kubernetes:
          version: 1.27.8
        name: worker-large
        machine:
          type: m3.large.x86
          image:
            name: flatcar
            version: 0.0.0-stable
          architecture: amd64
        maximum: 1
        minimum: 1
        maxSurge: 1
        maxUnavailable: 1
        providerConfig:
          apiVersion: equinixmetal.provider.extensions.gardener.cloud/v1alpha1
          kind: WorkerConfig
          reservationIDs:
            - SOMESPECIFICID
          reservedDevicesOnly: true
        zones:
          - fr2
        systemComponents:
          allow: true
        machineControllerManager:
          machineDrainTimeout: 2h0m0s
          machineCreationTimeout: 50m0s

Instead there should be a flag like use all disks that in turn adds a unit file to the list of unit files following https://www.flatcar.org/docs/latest/setup/storage/mounting-storage/

[gardener-robot]

@RiRa12621 Label area/enhancement does not exist.