Move freezing of Nonce to 4k/f from the end of the epoch.

[JaredCorduan]

Fix the Shelley spec errata issue 17.3 (#1914) with a switch on the major protocol version.

[JaredCorduan]

We are not going to change this for Babbage. We will do it sometime in preparation for Ouroboros Genesis.

[JaredCorduan]

This is related to #1914