Refactor distribution types to return Result (#470)

## Summary

A variety of small refactors to the distribution types crate to (1)
return `Result` if we find an invalid wheel, rather than treating it as
a source distribution with a `.whl` suffix, and (2) DRY up some repeated
code around URLs.

crates/puffin-resolver/src/error.rs

@@ -50,6 +50,9 @@ pub enum ResolveError {
     #[error("Package `{0}` attempted to resolve via URL: {1}. URL dependencies must be expressed as direct requirements or constraints. Consider adding `{0} @ {1}` to your dependencies or constraints file.")]
     DisallowedUrl(PackageName, Url),
 
+    #[error(transparent)]
+    DistributionType(#[from] distribution_types::Error),
+
     #[error("Failed to fetch wheel metadata from: {filename}")]
     RegistryBuiltDist {
         filename: String,