Add a filesystem to provide simplified access to GCP VM metadata

[hairyhenderson]

(just like #321, but for GCP)

I'd be useful to have a filesystem like gcpmetafs (or something) that can handle gcp+meta:// URLs.

This'd provide access to the GCP VM metadata service.

This vaguely came up here - hairyhenderson/gomplate#891 (comment) - I'd like to move forward with that.

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[github-actions]

This issue is stale because it has been open for 60 days with no activity. Remove stale label or comment or this will be automatically closed in a few days.

[github-actions]

This issue is stale because it has been open for 60 days with no activity. Remove stale label or comment or this will be automatically closed in a few days.

[github-actions]

This issue is stale because it has been open for 60 days with no activity. Remove stale label or comment or this will be automatically closed in a few days.

[hairyhenderson]

huh, weird... stalebot not behaving as it should 🤔