chore: add dylib downloader and validator

[ethanndickson]

First PR for #2.

This PR adds an abstraction for downloading & validating the dylib from a Coder server, and the network extension scaffolding.

It also adds a TunnelHandle type for owning the pair of pipes passed to the dylib, and the handle to the dylib itself.

You cannot create a unit test target that targets a System Extension. So, this PR extracts the portion of the network extension that we'd like to test into it's own Framework, VPNLib.

Of note is that SwiftProtobuf doesn't have a stable ABI (as it doesn't use library evolution), so the Framework has the Build libraries for distribution setting disabled. This shouldn't effect anything. Exporting the SwiftProtobuf types should be fine provided we don't import SwiftProtobuf in to the VPN target as well.

[ethanndickson]

• chore: extract CoderSDK to framework #19
• chore: add network extension manager #18
• chore: add dylib downloader and validator #16 👈 (View in Graphite)
• main

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[ethanndickson]

Merge activity

• Jan 13, 11:47 PM EST: A user started a stack merge that includes this pull request via Graphite.
• Jan 13, 11:48 PM EST: A user merged this pull request with Graphite.