Manually create unique_ptr in various pass adaptors

This avoids creating tons of make_unique template instantiations. And we
only create a unique_ptr of the actual pass concept type, rather than
creating a unique_ptr of the pass model subclass then casting it to the
pass concept type.

This reduces the work spent compiling PassBuilder.cpp from 83M -> 73M
instructions according to perf stat.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D110784