Is your feature request related to a problem? Please describe.
There seems to be no way to allow breaking end crystals in WorldGuard, so anyone that wants custom end island cannot allow just breaking End Crystals, which is nuts as this is vanilla mechanic.

Describe the solution you'd like
Either have a break-entities or put end crystals under the interact flag (Or break-blocks) to allow us to just allow breaking end crystals.

Describe alternatives you've considered
Using WorldGuardExtraFlags (No alternative solution)

Additional context
People make custom end worlds for dragon spawns and don't want people to destroy them, you can easily get the crystals to respawn using setblock or WE at the dragon spawn event, which allows you to have a custom end island, but the ONLY way to allow people to break crystals is to give them build! So players can build, put signs in the place of crystals and just break things.