Create the DetectorFailure class and its subclasses.

Add the DetectorFailure class and its subclasses to let the assistant
application  know what went wrong during using the hotword detector.

Subclasses as below:
    HotwordDetectionServiceFailure class
    SoundTriggerFailure class
    UnknownFailure class
    VisualQueryDetectionServiceFailure class

Bug: 256780491
Bug: 261012843
Test: atest CtsVoiceInteractionTestCases

Change-Id: I5a35a0098afb77898e49f8c28b66ccf058e5e8dd