fix: Make --whole-archive work with linker plugins

[davidlattimore]

Fixes #1897

[davidlattimore]

I considered changing has_archive_semantics so that all callers would treat objects with --whole-archive as if they didn't have archive semantics. One of the callers was the code that handles --exclude-libs, so I added a test that checks the interaction of --exclude-libs and --whole-archive. The test demonstrated that they shouldn't interact, i.e. that having --whole-archive prevent --exclude-libs from acting would be wrong, so I went with just updating the behaviour for the linker plugin driver.