Use module account and sub accounts for ICS20 escrow addresses

[colin-axner]

Summary

Currently, ICS20 escrow addresses use a prefix and hash of the port/channel to generate the address. Careful consideration was made to ensure these addresses would not conflict with one another. Now that v0.43 of the SDK has implemented ADR 28, we should eventually migrate our escrow addresses to using a module account and sub accounts for each escrow address.

This solution is low priority since the current implementation was determined to be secure, but only with the portID "transfer". I'm unsure if using the ADR 28 solution would allow us to lift the maximum channel sequence requirement

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned

[colin-axner]

see comment for more details