DESERIALIZER: Refactor the constructor setting API

DESERIALIZER: Refactor the constructor setting API

It's not the best idea to set a whole bunch of parameters in one call,
that leads to functions that are hard to update.  Better to re-model
this into several function made to set one parameter each.

This also renames "finalizer" to "constructor", which was suggested
earlier but got lost at the time.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/12544)