shared/api: Add return parameter names to appease static analysis

Signed-off-by: Mark Bolton <mark.bolton@canonical.com>

shared/api/instance.go

@@ -6,7 +6,7 @@ import (
 )
 
 // GetParentAndSnapshotName returns the parent name, snapshot name, and whether it actually was a snapshot name.
-func GetParentAndSnapshotName(name string) (string, string, bool) {
+func GetParentAndSnapshotName(name string) (parentName string, snapshotName string, isSnapshot bool) {
 	fields := strings.SplitN(name, "/", 2)
 	if len(fields) == 1 {
 		return name, "", false