[Shiden] Kusama - AssetHub Migration

[PierreOssun]

Kusama - AssetHub migration is happening on Tue October 7th.

Shiden sovereign KSM account on Kusama:
https://kusama.subscan.io/account/F7fq1jNy74AqkJ1DP4KqSrWtnTGtXfNVoDwFhTvvPxUvJaq

Shiden sovereign KSM account on AssetHub:

https://assethub-kusama.subscan.io/account/FBeL7EC3qF4yM29mP1Qx6CL9G8abwiUZSsNWezRo7z3mjGW

There is several things to do:

• 1. Accept AssetHub as KSM reserve (runtime-1700)
• 2. Remove Kusama as KSM reserve

EDIT: Not doing (3) as trasnfer_assets is a blacklisted call already:

• (Unrelevant) 3. Deactivate calls that can use Kusama as reserve: Throw error on transfer_assets and (limited_)reserve_transfer_assets by using latest version on pallet_xcm (doc here, GiHub issue here)
• 4. For XTokens deactivate calls that use Kusama as reserve: configure ReserveProvider to return None during migration, and AssetHub (Para 1000) after migration
• 5. XCM root Call to transfer KSM from Kusama sibling to AssetHub sibling

Timeline:

• On Monday 6th: runtime upgrade to ship 2, 3 an 4.
• On Monday 6th after the update is live. Run 5
• On Wednesday 8th after migration: runtime upgrade to
  • Reconfigure ReserveProvider to use AssetHub (Para 1000)
  • (when ready on Parity side or use pre-fix version) update pallet_xcm to re-allow transfer_assets's calls