Restore support for exporting INTERFACE with missing dependencies

Since commit c16acd35b3 (GenEx: Add support for custom transitive link
properties, 2024-05-09, v3.30.0-rc1~82^2) evaluation of
`TRANSITIVE_LINK_PROPERTIES` by `install(EXPORT)` enables discovery of
missing dependencies on INTERFACE libraries that we did not previously
diagnose.  This regressed existing projects that relied on such
non-diagnosis.  Although commit 2fc9e482a9 (Evaluation of
TRANSITIVE_LINK_PROPERTIES isn't considered a usage, 2024-07-05) fixed
this, it also made a significant change to the `UseTo` infrastructure
that may have other subtle effects.  Replace the fix with an approach
that explicitly models suppression of the relevant diagnostics.

Fixes: #26108
5 files changed