/usr/lib/x86_64-linux-gnu/libKF5Mime.so is in libkf5mime-dev 17.12.3-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libKF5Mime.so.5abi2
/usr/lib/x86_64-linux-gnu/libKF5Mime.so.5abi2