nft: calculate cache requirements from list of commands

nft: calculate cache requirements from list of commands

This patch uses the new list of commands to calculate the cache
requirements, the rationale after this updates is the following:

 #1 Parsing, that builds the list of commands and it also calculates
    cache level requirements.
 #2 Cache building.
 #3 Translate commands to jobs
 #4 Translate jobs to netlink

This patch removes the pre-parsing code in xtables-restore.c to
calculate the cache.

After this patch, cache is calculated only once, there is no need
to cancel and refetch for an in-transit transaction.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Phil Sutter <phil@nwl.cc>