Describe changes

The initial vault package is monolithic, difficult to debug, and hard to add new features to.

This refactoring in a new vault package separates concerns.

Progress:

• account module ✅
• key agent module ✅
• @palladxyz/key-management package refactor ✅
• • add encrypted child private key to derived credentials ✅
• • decrypt the encrypted child private key with passphrase to use in all signing operations. This reduces the need to always decrypt root key across many functions and only for deriving new credentials. ✅
• • use passphrase in all operations requiring use of private keys
• credentials module ✅
• refactor wallet to use new vault package ✅

Multichain refactor:

• refactoring everything 🚧