Look into how alliance assets can be removed and delegations returned

[javiersuweijie]

Currently, in order to remove an alliance asset. Governance needs to set reward weights first to zero and make sure all delegators un-delegate before another proposal can be raised to delete the alliance.

Proposal: Update the delete alliance flow to perform the below steps:

1. Move delegator assets to a module account
2. Allows delegators to claim/un-delegate their assets
3. Delete the alliance asset