New advancement to reveal fireworks' use with Elytra to new players

Adding an advancement for using a firework while gliding with an elytra would help new players realize that fireworks can, indeed, be used to boost elytra flight.

Currently, there is no in-game way for a new player to find out that it is possible to use fireworks to boost elytra flight. It is very unlikely for a new player to realize this on their own. Adding an advancement, or even some other in-game hint, to let new players know that fireworks can be used with elytra, would let new players know about this game mechanic, which is near essential for large-scale projects.