The role of the tagging keys in the future protocol.

[IlyasRidhuan]

The tagging key is currently unused in the protocol, there is a draft AZIP-10 that is looking to re-purpose the tagging keys to be kind of enshrined signing keypair that users can leverage outside of the authwit scheme.

At some point in the review, @iAmMichaelConnor wrote this, which summarises into the following points

1. Maybe the Tpk could still be useful (under-explored)
2. Maybe an additional "migration pk" is needed, in addition to a new signing key
3. Maybe authwits can be used instead of a signing key.

Let's discuss!