Fix For Redacting Readonly Properties

[thomashmolina]

Description

Related to this issue. This enables redacted values of readonly properties to appear in logs.

Added 2 additional tests to verify that readonly properties can be redacted.

Expected Behavior

Logs should show redacted values of readonly properties if they defined in the $sensitive_keys array.

Fix

traverseObj checks if an object has readonly properties. If an object has readonly properties, it uses an instance of \stdClass to record redacted versions of the value instead of trying to modify a readonly property.