Increase End City Generation and Elytra Availability

It is very disheartening to work so hard to get past the ender dragon only to end up spending literal hours and hours hoping to find an End City and hoping that the end city has a ship with elytra. The elytra have become an integral part of the game and are essential for people who really want to explore the endless world in an even moderately efficient manner. We shouldn't have to slip into creative or spectator mode to find the End Cities. Shulker boxes are also critical given how many blocks exist and how inventory management has not kept up with increased variety of blocks. Make End Cities generate more often and raise the percentage of End Cities with elytra.