feat: reset team on refund

[rflechtner]

Suggested change to avoid unexpected changes to currencies and issuances while refunding. This resets all asset teams to the pool account when calling start_refund.

This is waiting for a runtime implementation of our new pallet so that we can see the impact on the transaction weight that this has.

Checklist:

• I have verified that the code works
  • No panics! (checked arithmetic ops, no indexing array[3] use get(3), ...)
• I have verified that the code is easy to understand
  • If not, I have left a well-balanced amount of inline comments
• I have left the code in a better state
• I have documented the changes (where applicable)
  • Either PR or Ticket to update the Docs
  • Link the PR/Ticket here

[Dudleyneedham]

@rflechtner What is this?

[rflechtner]

@rflechtner What is this?

We can pick this up after trialing the pallet on a testnet. We're currently not quite sure if we want to reset the asset admins when the pool moves to refunding state. This would do it, but would need to be benchmarked properly.