Should we remove forwarding references from PTE solvers?

The segfault on HIP was caused by an access-out-of-scope error caused by passing pointers by reference into the PTE solvers. See #437 . Perhaps we should consider removing the forwarding references and pass only by value into the PTE solvers (with the exception of PTE Solver Base, which requires pass-by-reference as it is used as the first part of the derived class constructors).

Ping @jhp-lanl @jdolence @dholladay00 @mauneyc-LANL and @rbberger for feedback