This commit disables the windows-only minidump plugin and enables the new
cross-platform plugin for windows minidump files. Test decorators are adjusted to
reflect that: windows minidump tests can now run on all platforms. The exception
is the tests that create minidump files, as that functionality is not available
I've checked that this works on windows and linux. If it goes well on the bots,
I'll delete the old plugin in a follow-up.