Upgrade Pallets to FRAME v2

[shawntabrizi]

There are a number of custom Polkadot pallets in this repo, and we could use help to migrate them to the new v2 macro.

The pallets which are already live need to check that they won't break, but new pallets like the onboarding systems should get migrated before they are put live on the network.

• auctions (Update auctions pallet to FRAME v2 #3031)
• claims (Update claims pallet to FRAME v2 #3032)
• crowdloans (Update crowdloan pallet to FRAME v2 #3036)
• mmr (Update mmr pallet to FRAME v2 #3061)
• registrar (Update registrar pallet to FRAME v2 #3063)
• sudo wrapper (Update para sudo wrapper pallet to FRAME v2 #3074)
• purchase (Update purchase pallet to FRAME v2 #3075)
• slots (Update slots pallet to FRAME v2 #3218)
• runtime > parachains (a lot in here)

[shaunxw]

XCM sender doesn't need migration as it's not a pallet. Migrations in runtime > common are done.