implement FIP-0115

[LesnyRumcajs]

Summary

The FIP-0115 seems to be mostly approved; the change is client-side so we need to implement it in Forest.

There's a reference implementation in Lotus. PR here.

This is also a good opportunity to do a more hands-on review of the FIP.

Completion Criteria

• implement FIP-0015 in Forest
• ensure the logic matches the FIP text

Additional Links & Resources

There might be additional changes incoming in separate PRs; the reference one might not be the only one.