feat(library/standard/data/nat/order): add le_decidable, lt_decidable, ge_decidable, gt_decidable

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
chore(library/standard/data/nat/order): remove unnecessary 'proofs'

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
checkpoint
checkpoint
checkpoint
checkpoint, use dash.el