Reminder - remove outdated HexPattern/HexSignature codecs at some point #1289

The pre-#1270 HexPattern and HexSignature codecs were kept around so that updating to build 53 wouldn't void all stored hexes from earlier 1.21 builds. However, once a majority of people update to build 53 or later, those old codecs will become irrelevant. They aren't even useful for updating from 1.20 since the NBT->Component transition requires an entire datafixer which can go straight to the new encoding mechanism.

Consequently, we should remove the old codecs at some point - probably before the official 1.21 release?