CMakes `target_link_libraries()` supports certain keywords to
only enable specific libraries for specific CMake configurations.
We now try our best to replicate this for Meson dependencies.
Fixes#9197
Both of these are artifacts of the time before Dependency Factories,
when a dependency that could be discovered multiple ways did ugly stuff
like finding a specific dependency, then replacing it's own attributes
with that dependency's attributes. We don't have cases of that left in
the tree, so let's get rid of this code too
This allow mypy to catch cases where we accidently assign the dependency
name to the type_name, as it sees them as having different types (though
at runtime they're all strings).