daemon/meson.build: add install_rpath to kresd

This fixes the default use-case for developers when they put their install prefix somewhere where the system LD_LIBRARY_PATH does not point. Before this, kresd would fail to start after ninja install because it would not be able to find the libkres.so library.

The original workaround to this was to use meson configure -Ddefault_library=static, but firstly, we would like it to be working with the default settings, and secondly, we would like to have it as similar to what most users will encounter as possible.