feat: schnorr signing workaround

[alfonsobries]

Summary

https://app.clickup.com/t/86du602g6

• Adds a workaround to sign with Schnorr using JS
• Adjusts serialization/deserialization
• Adds multisignature registration and tests
• Renames delegate registration to validator registration
• Removes some code related to deprecated transactions type; another task exists to cleanup more stuff

Checklist

• Documentation (if necessary)
• Tests (if necessary)
• Ready to be merged