Shared library stubs can be used for linking, but not at runtime.
Their role is similar to import libraries on Windows, so represent
their location with the `IMPORTED_IMPLIB` target property.
Fixes: #24940
The OLD behaviors of all policies are deprecated, but only by
documentation. Add an explicit deprecation diagnostic for policies
introduced in CMake 3.19 and below to encourage projects to port
away from setting policies to OLD.
Fix logic added by commit 359c500a24 (cmTarget: Raise error if imported
target location is not set, 2020-08-08, v3.19.0-rc1~273^2) to exclude
INTERFACE libraries from the policy. They have no location.
Fixes: #21470
Previously we would synthesize <TARGET_NAME>-NOTFOUND as the location. This
would then end up on the link line and cause build failures.
Policy CMP0110 is added to control this behaviour.
Fixes#19080, #19943.
