feat: add support for 'import' content type in Proxmox file resources

[Vaneixus]

Signed-off-by: Marco Attia [email protected]

Contributor's Note

• I have added / updated documentation in /docs for any user-facing features or additions.
• I have added / updated acceptance tests in /fwprovider/tests for any new or updated resources / data sources.
• I have ran make example to verify that the change works as expected.

Proof of Work

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Relates #1913

[Vaneixus]

It's not ready yet. but I am open to any comments thus far.

[Vaneixus]

One of the things I need to check and implement is maintain Backwards compat with Proxmox version < 8.4, since those will still need to use the SSH method.

[Vaneixus]

I force-pushed to sign the commits since I do not have access to my signing key in the devcontainer. nothing has changed, except, well, a new commit.