Offer a Bandwidth action for devices

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What problem are you facing?

I would like to see how much bandwidth my devices are using, using packet-cli.

How could the Equinix Metal CLI help solve this problem?

metal device bandwidth --id 1234 --since "2021-02-01 1:00:00 UTC" --until "2021-02-02 1:00:00 UTC"

(Whatever date format makes sense)

How should this be rendered? (question for whoever is implementing this)

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The date fields would benefit from #127

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This would depend on https://deploy.equinix.com/developers/api/metal#tag/Devices/operation/findInstanceBandwidth