provide ablity to check whether component field addresses eid

[caryoscelus]

a bit of context: i'm dealing with serialization rn, and find builtin serialization mechanism lacking in documentation. i'm getting some arraybuffer, but have no idea of its format. i haven't dug too far, but it does look like it's a binary format. i would like to have text-based serialization as alternative, so i'm building my own. with a bit of customizing defineComponent (along the lines of #111 (comment)), i'm able to jsonify entities, but in order to make proper (de)serialization i need to handle eids

it seems like whether a store contains eids or not can be determined by $isEidType field, but that symbol doesn't seem to be available for library users. can we have some way to query this information from outside library internals?

[pietrovismara]

You can use this "trick" to retrieve bitecs internal symbols:

const $isEidType= Object.getOwnPropertySymbols(Component.property).find(
	(symbol) => symbol.toString() === Symbol('isEidType').toString(),
) as symbol;

It works also on world and on components.

[caryoscelus]

@pietrovismara this seems a bit too hacky to be reliable: anything not in API can be changed without warning. for now i simply forked repo to use in the project where i need this, but having official solution would still be better