Not sure why all these includes were missing, but it's breaking builds
for some users:

https://bugs.gentoo.org/show_bug.cgi?id=652142

(Added to all files with a reference to std::unique_ptr)

Backport of core PR12859:
https://github.com/bitcoin/bitcoin/pull/12859/files

This has been heavily adapted to our codebase.
I grepped all the units (.h and .cpp) including memory, the ones using
std_unique_ptr and used the diff to track down the needed inclusions.

ninja check bench-bitcoin

Run the gitian builds.