Include output information in the package page response

As this will be useful for QA to say whether the package builds reproducibly
or not.

guix-data-service/model/derivation.scm

@@ -44,6 +44,7 @@
             select-derivation-by-file-name
             select-derivation-by-file-name-hash
             select-derivation-outputs-by-derivation-id
+            select-derivation-outputs-by-derivation-file-name
             select-derivation-sources-by-derivation-id
             select-derivation-references-by-derivation-id
             select-derivation-source-file-by-store-path
@@ -1158,6 +1159,31 @@ ORDER BY derivation_outputs.name"))
             (string=? recursive "t"))))
    (exec-query conn query (list (number->string id)))))
 
+(define (select-derivation-outputs-by-derivation-file-name conn file-name)
+  (define query
+    (string-append
+     "
+SELECT derivation_outputs.name, derivation_output_details.path,
+  derivation_output_details.hash_algorithm, derivation_output_details.hash,
+  derivation_output_details.recursive
+FROM derivation_outputs
+INNER JOIN derivation_output_details ON
+  derivation_outputs.derivation_output_details_id = derivation_output_details.id
+INNER JOIN derivations
+  ON derivation_outputs.derivation_id = derivations.id
+WHERE derivations.file_name = $1
+ORDER BY derivation_outputs.name"))
+
+  (map
+   (match-lambda
+     ((name path hash_algorithm hash recursive)
+      (list name
+            path
+            hash_algorithm
+            hash
+            (string=? recursive "t"))))
+   (exec-query conn query (list file-name))))
+
 (define (select-derivation-inputs-by-derivation-id conn id)
   (define query
     (string-append