fix: more informative error when effects run in an infinite loop

[Rich-Harris]

Supersedes #16247, closes #16092.

Today, if you have an effect that runs in an infinite loop, you get this somewhat unhelpful log:

Expanding the array usually reveals 10 copies of the same compiled function:

While you can click through to the [[FunctionLocation]]...

...even that doesn't necessarily tell you where the offending state change occurred.

We can do better. In this PR, we track the site of updates to state that occur inside an effect, then if we do encounter an infinite loop we can pinpoint those sites:

This works for things like array mutations, and even works for effects that ping-pong (as opposed to the probably-more-common case in which an effect invalidates itself):

$effect(() => {
  a = b + 1;
});

$effect(() => {
  b = a + 1;
});

Better yet, this is actually simpler than what we currently have — the implementation of infinite_loop_guard can be much leaner, and log_effect_stack and dev_effect_stack are no more.

This PR also adds an explanation of the error. For things like this I prefer progressive disclosure (i.e. link to the docs when it becomes relevant) rather than adding stuff that you have to read upfront, so I view this as an alternative to #16247.

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