fix(services/swift): add missing copy capability flag (#7204)

fix(services/swift): declare copy capability that is already implemented

The copy() method is fully implemented in the SwiftBackend Access trait
but copy: true was missing from the Capability struct, so callers had
no way to know the operation was available.

Author: benroeder

core/services/swift/src/backend.rs

@@ -152,6 +152,8 @@ impl Builder for SwiftBuilder {
 
                             delete: true,
 
+                            copy: true,
+
                             list: true,
                             list_with_recursive: true,