personalization: refactor SdKey
Refactor SdKey (and subclasses) to the new ConfigurableParameter
implementation style, keeping the same implementation.
But duly note that this implementation does not work!
It correctly patches pe.decoded[], but that gets overridden by
ProfileElementSD._pre_encode().
For a fix, see I07dfc378705eba1318e9e8652796cbde106c6a52.
Change-Id: I427ea851bfa28b2b045e70a19a9e35d361f0d393
