Structures Deleted Property

[UnseenFaith]

Please describe the problem you are having in as much detail as possible:

Currently the only way to check if a certain structure in Discord.js is stale is by checking the cache or crosschecking with the API.

Ex:
A Message is created and then deleted for whatever reason. The message object is removed from the API and the cache, but the object won't be GCed immediately. Now you have a stale message object and the only way to check if this message object is stale or not is by checking the cache
and/or trying to fetch the message back from the API.

This applies for pretty much any structure that can be deleted from the API.

It'd be nice to have a property on the structure that would be set to true, i.e. <Message>.deleted, when the Delete WS Event comes in for that structure.

<Structure>.deletable only checks whether or not the Bot has the Permissions to delete it, not if its already been deleted or not.

Edit: This is doesn't take in the fact that we have Events for those deletion purposes. I think the property could still be warranted as useful disregarding those.