Ensure that version resolution works offline

And so, even for unpinned package. In this case, we can't do a HEAD request. So we fallback by looking at what's available in the cache and using the most recently downloaded version from the cache. This is only a best effort as the most recently downloaded one may not be the actual latest. But common, this is a case where (a) someone didn't pin any version, (b) is trying to build on in an offline setup. We could possibly make that edge-case better but, let's see if anyone ever complains about it first.

crates/aiken-project/src/deps/downloader.rs

@@ -11,6 +11,7 @@ use crate::{
     error::Error,
     package_name::PackageName,
     paths::{self, CacheKey},
+    telemetry::EventListener,
 };
 
 use super::manifest::Package;