reduce repetitive, nested structs by proving a defaults package

#300 had

> Nested Structs make writing code confusing

#300 suggested a number of ideas here.

* Using tags/sizing and reducing the number of nesting done
* Add more default templates users can use. For more specific structs, such as tpmu.PublicParams adding all most commonly used would be nice to have for users. For broader structs like tpmt.Public, having examples to follow should suffice.
* Add a way to pick common combinations of tpma.Object aside for manually setting true for each specific field.

Start by reading issue #300 and locating the tpmu.PublicParams, tpmt.Public, and tpma.Object structs mentioned here. Compare the proposed defaults, tags or sizing changes, and common combinations before defining a focused scope; done should mean one agreed defaults-package design with clear examples and validation criteria.

Written by the indexing model from the issue text.