Add option for verifiable publish/import

[maxzinkus]

I plan to add this as an optional feature on publish & import.

publish creates a compressed archive, and import unpacks it into a ~/.macpine VM directory.

Adding verifiability to this process would allow for:

• trustworthy sharing of imported VMs
• encrypted & authenticated backups of VMs

age is a modern file-based authenticated-encryption tool written by a renown author in the cryptography community.

age can encrypt & authenticate:

• symmetrically, with a password
• asymmetrically, to an age-keygen-generated public key, or to an ssh-keygen ssh public key

Symmetric encryption can be used for secure backups or ease-of-use in verifiable sharing. Asymmetric encryption can be used to encrypt VMs to a specified recipient, including by using their publicly-listed GitHub SSH keys (example: https://github.com/maxzinkus.keys).

[maxzinkus]

TODO @maxzinkus: import age as a Go mod rather than system dep, and call it programmatically instead of using exec. Refer to FiloSottile/age#436

[maxzinkus]

@idroz once I have time to wrap this one up, maybe it could be time for v0.11 -- and maybe a round of hackernews / reddit / etc postings! I imagine the traffic is positive for your company and the new features are pretty fun and improve user QoL, so they could draw even more traction :)

[idroz]

I was thinking of doing a tightening up of the docs/adding some fun examples and doing the 0.11 release with features as they are now :) With the API stabilising and verifiable publish/import it may be time to put a roadmap together for 1.0 release?

Certainly hn/reddit awareness round would be good and I can put that together once 0.11 is out!

[maxzinkus]

#127 is ready for review!

[maxzinkus]

and- sounds good. I don't have any other API-level ideas or changes in the near term :)

[maxzinkus]

@idroz I messed up and accidentally merged this PR (#127) while trying to re-synchronize other changes to main into it. I tried to revert it (#134) but that seems to have made even more of a mess.