Revisit silk elytra break behavior

As it stands, when a silk elytra reaches 1 point of durability, it can no longer be used for flight, but it isn't converted into a "broken" elytra and remains equipped. If the player then takes some sort of damage (say, by falling from a great height), the silk elytra has a chance of breaking.

Now, that's far from catastrophic, as silk elytra are craftable and thus easily replaceable. But is this actually the dynamic I want? Is it even consistent that silk elytra won't break completely from flight but will from damage?

I dunno. Gotta think about it.

The issue names no files, tests, or entry points. Review the current silk elytra durability and damage behavior, then determine which behavior is intended and document the decision. Done requires an explicit, consistent outcome for flight at 1 durability and subsequent damage.