Unconditionally create linking context from `swift_{binary,test}`'s direct `srcs`.
Unconditionally create linking context from
`swift_{binary,test}`'s direct `srcs`.

Also set `alwayslink = True`, and don't pass the compilation outputs to
`register_link_binary_action` since they will be propagated from the
said linking context.

This avoids the possible symbol duplication, as previously the same
object files would be passed to the linker twice.

bazelbuild/rules_swift,bazelbuild/rules_swift