Use hasher to compute resolution hash (#5495)

## Summary

Addressing one TODO. This should be more efficient.

crates/cache-key/src/digest.rs

@@ -1,22 +1,34 @@
-use std::hash::Hasher;
-
 use crate::cache_key::{CacheKey, CacheKeyHasher};
+use seahash::SeaHasher;
+use std::hash::{Hash, Hasher};
 
 /// Compute a hex string hash of a `CacheKey` object.
 ///
-/// The value returned by [`digest`] should be stable across releases and platforms.
-pub fn digest<H: CacheKey>(hashable: &H) -> String {
+/// The value returned by [`cache_digest`] should be stable across releases and platforms.
+pub fn cache_digest<H: CacheKey>(hashable: &H) -> String {
+    /// Compute a u64 hash of a [`CacheKey`] object.
+    fn cache_key_u64<H: CacheKey>(hashable: &H) -> u64 {
+        let mut hasher = CacheKeyHasher::new();
+        hashable.cache_key(&mut hasher);
+        hasher.finish()
+    }
+
     to_hex(cache_key_u64(hashable))
 }
 
+/// Compute a hex string hash of a hashable object.
+pub fn hash_digest<H: Hash>(hashable: &H) -> String {
+    /// Compute a u64 hash of a hashable object.
+    fn hash_u64<H: Hash>(hashable: &H) -> u64 {
+        let mut hasher = SeaHasher::new();
+        hashable.hash(&mut hasher);
+        hasher.finish()
+    }
+
+    to_hex(hash_u64(hashable))
+}
+
 /// Convert a u64 to a hex string.
 fn to_hex(num: u64) -> String {
     hex::encode(num.to_le_bytes())
 }
-
-/// Compute a u64 hash of a [`CacheKey`] object.
-fn cache_key_u64<H: CacheKey>(hashable: &H) -> u64 {
-    let mut hasher = CacheKeyHasher::new();
-    hashable.cache_key(&mut hasher);
-    hasher.finish()
-}

crates/cache-key/src/lib.rs

@@ -1,6 +1,6 @@
 pub use cache_key::{CacheKey, CacheKeyHasher};
 pub use canonical_url::{CanonicalUrl, RepositoryUrl};
-pub use digest::digest;
+pub use digest::{cache_digest, hash_digest};
 
 mod cache_key;
 mod canonical_url;