Merged requested to merge ondrej/cherry-picked-netmgr-v9_16 into v9_16
This is cherry-picked branch with all changes that has been done to the main branch (sans the changes to
lib/isc/netmgr is almost identical now (the extra stuff in main is non-related to netmgr, but to a coding style).
I believe this also closes #2042 (closed) and solves part of #2071 (closed).
Closes #2042 (closed)