feat: subscribeChanges

[samwillis]

This adds a few public APIs:

• collection.derivedChanges is a tanstack/store Derived state, it is replaced with the latest changes (insert/update/delete) each time the derived state changes. This can be used inside an Effect along with other collections to essentially subscribe to a set of charges across the collections. This will be the foundation of the IVM queries.
• collection.currentStateAsChanges returns the current state as a set of inserts. It's needed to bootstrap the initial state of a query.
• collection.subscribeChanges is a thin wrapper of the above as a higher level public api

[changeset-bot]

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Latest commit: 2ea79ce

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[pkg-pr-new]

examples/react/todo

npm i https://pkg.pr.new/@tanstack/optimistic@30

npm i https://pkg.pr.new/@tanstack/react-optimistic@30

commit: 2ea79ce

[KyleAMathews]