feat(rt): add CRC32C algorithm (#724)

Author: lauzadis

.changes/f01f5a37-e7ca-4786-a0a9-fd1ed6adf127.json

@@ -0,0 +1,6 @@
+{
+  "id": "f01f5a37-e7ca-4786-a0a9-fd1ed6adf127",
+  "type": "feature",
+  "description": "Add CRC32C hashing algorithm",
+  "issues": "awslabs/aws-sdk-kotlin/#727"
+}

runtime/hashing/common/src/aws/smithy/kotlin/runtime/hashing/Crc32.kt

@@ -12,6 +12,17 @@ public abstract class Crc32Base : HashFunction {
     override val digestSizeBytes: Int = 4
 
     public abstract fun digestValue(): UInt
+
+    override fun digest(): ByteArray {
+        val x = digestValue()
+        reset()
+        return byteArrayOf(
+            ((x shr 24) and 0xffu).toByte(),
+            ((x shr 16) and 0xffu).toByte(),
+            ((x shr 8) and 0xffu).toByte(),
+            (x and 0xffu).toByte(),
+        )
+    }
 }
 
 /**