Merge from vendor branch TNF:

Merge from vendor branch TNF:
Import dtpstree-1.0.3 as sysutils/dtpstree.
Based on PR#43661 by Douglas William Thrift.

DT PS Tree shows running processes as a tree. It is a reimplementation of
pstree from PSmisc for FreeBSD, NetBSD, OpenBSD, DragonFly BSD, and possibly
other modern BSD variants. It also works without /proc and will show the full
set of processes in a jail even if init is not present.