Add gir targets to the dependencies sources attribute and other meson cleanups.
Review Request #939 — Created Sept. 25, 2021 and submitted — Latest diff uploaded
Adding the gir targs to the dependency object of the library allows us to be able to use the dependency in a gnome.generate_gir for a library that consumes our api regardless of if it's a system install or a subproject.
Modified the gplugin subproject in pidgin and used these changes to verify that it fixed the current build issues over there.