PAS to define parachain time slot

[hbulgarini]

Until coretime is in place, we need to define how are we going to manage the slots for parachains.

I kind of see two two time slots:

1. 1 year for parachains being on Polkadot/Kusama.
2. 2 weeks for builders that want to try Paseo?

Also we should limit the amount of parachains on the group two, i think.

Once core time is in place this process will be decomissioned.

[al3mart]

Closed by #44

[hbulgarini]

#44