use a request to poll progression for seed fetching

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
SpuriousSeedAnnihilator: download seeds with the key-value store

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
don't use a reference to compute the smallest handle

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
flip the computed paths between shorter seeds too

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>