TruthTable improvements: structural equality and delete sort (backport #2935) (#2936)

* TruthTable improvements: structural equality and delete sort (#2935)

We had implemented equals, but not hashCode. This commit also changes
the implemental of equals to just use the underlying values instead of
wasting the compute calling .toString.

Delete TruthTable.sort, it is unused.

(cherry picked from commit b5d9c08b

)

* Restore and deprecate TruthTable.sort

Co-authored-by: Jack Koenig <koenig@sifive.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>