Replaced the dynamic table type ArtifactLocation with struct keys

The original is present in comment form for reference

pkg/artifactstore/common.go

@@ -7,7 +7,7 @@ import (
 
 // XX: static types: split by type?
 // Restrict the keys / values for ArtifactLocation and centralize the common ones
-// here 
+// here
 const (
 	AF_VAL_BUCKET_RESULTS = "results"
 	AF_VAL_BUCKET_PACKS   = "packs"
@@ -20,7 +20,9 @@ type ArtifactLocation struct {
 	// For example, a simple key-value pair could be "path" -> "/path/to/artifact.tgz".
 	// Alternatively, a more complex example could be "bucket" -> "example", "key" -> "UNIQUE_ARTIFACT_IDENTIFIER".
 	// XX: static types
-	Data map[string]string `json:"data"`
+	// Data   map[string]string `json:"data"`
+	Key    string // location in bucket
+	Bucket string // which bucket: packs or results
 }
 
 // deriveKeyFromSessionId generates a key for a query pack based on the job ID