Implement ASPA validation and reload logic on ASPA set changes.

Implement ASPA validation and reload logic on ASPA set changes.

For this use the validation state (vstate) in struct prefix and
struct filterstate to store both the ASPA and ROA validity.
Introduce helper functions to set and get the various states for
struct prefix and make sure struct filterstate is also setup properly.
Change the ASPA state in rde_aspath to be AFI/AID and role independent
by storing all 4 possible outcomes. Also add a ASPA generation count
which is used to update the rde_aspath ASPA state cache on reloads.
Rework the rde_aspa.c code to be AFI/AID and role independent. Doing
this for roles is trivial but AFI switch goes deep and is so unnecessary.
The reload is combined with the ROA reload logic and renamed to RPKI
softreload.

OK tb@