ClientXdsClient throws away exception information

While ClientXdsClient commonly uses approach like StructOrError to avoid creating exceptions, there are still exceptions that need to be caught. This is most frequently InvalidProtocolBufferException, but can also entail IllegalArgumentException, PatternSyntaxException, and maybe others.

Unfortunately, the fully causal chain and stack trace is being completely thrown away for these exceptions. At the _very least_ they should be logged at FINE or lower level. In cases that produce a Status, the cause would ideally be included as the Status cause. However, XdsLogger's API currently doesn't allow logging exceptions and StructOrError only supports simple strings.

CC @voidzcy, @dapengzhang0, @sergiitk