Currently the PDE QuickFixProcessor suggest to modify the manifest and
add an import package or a require bundle if it finds that a type is
missing, this is not useful for automatic manifest projects.

This changes the PDE QuickFixProcessor to skip import package proposal
for automatic manifest projects and instead of suggest require bundle to
add the bundle to the buildpath.

Fix https://github.com/eclipse-pde/eclipse.pde/issues/702