Emergency stop procedure

[t4sk]

0. Have 0 strategy approved by vault (this takes minimum 1 day timelock)
1. Pause vault. Users will not be able to deposit. Vault will not be able to invest strategy.
2. Switch to 0 strategy. This will exit current strategy, withdrawing all funds back to vault.
3. If 2 fails, call withdrawAll on vault and the switch to 0 strategy.