Implement SanitizedBridgeExtraInfoDescriptor class that encapsulates the sanitizing logic for bridge extra-info descriptors

Create the two classes SanitizedBridgeExtraInfoDescriptor and SanitizedBridgeExtraInfoDescriptorTest. SanitizedBridgeExtraInfoDescriptor should extend BridgeExtraInfoDescriptor all else analogously to legacy/trac#20549 (moved).