perf: bail early when traversing non-state

[dummdidumm]

We need to use deep_read to traverse all properties of an object inside legacy mode and inside actions, because the input we get could be a state proxy. This proxy will have fine-grained reactivity and therefore only update the signal at the location that got an update. In order to have interop with the coarse-grained "notify me when anything in that object changes" behavior, we need to setup up signals for all of the object's properties before they're potentially mutated.
This has a lot of overhead for large lists, and we can at least diminish in the "no state proxy" case by applying a sensible heuristic:

• If the value passed is a state proxy, read it
• If not, and if the value is an array, then bail because an array of state proxies is highly unlikely
• Traverse the first level of properties of the object and look if these are state, if not bail. State proxies nested further down are highly unlikely, too

part of #10637

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