crimson/common: use parameter pack for building future<>

crimson/common: use parameter pack for building future<>

it mirrors the way how seastar::make_ready_future() works. and more
importantly, it allows us to build interruptible_future in the same
way as we build plain seastar::future<> in-place. so we can, for
instance, create a future<tuepl<int,int>> using:

make_ready_future<tuple<int,int>>(1, 2)

instead of using

make_ready_future<tuple<int,int>>(make_tuple(1, 2))

Signed-off-by: Kefu Chai <kchai@redhat.com>