security: Stop automatically adding URLs from server-side load fetch calls to dependencies

[elliott-with-the-longest-name-on-github]

Closes #9803. This is a breaking change for security purposes.

This PR prevents server load function from implicitly depending on URLs passed to fetch. This is because dependencies from server load functions have to be sent to the client in order to be invalidated, which can leak secrets (if they're in the search params, for example).

If you understand the risk and want to keep the old behavior, you can set config.kit.dangerZone.trackServerFetchesPotentiallyExposingSecrets to true.

TODO:

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[Rich-Harris]

I think we can trim the option name down to trackServerFetches — we can explain the details in the inline documentation, and the dangerZone makes it clear that this is 'know what you're doing' territory

Suggested change

	/**
	* Automatically add server-side `fetch`ed URLs to the `dependencies` map of `load` functions. This will expose secrets
	* to the client if your URL contains them.
	*/
	trackServerFetchesPotentiallyExposingSecrets?: boolean;
	/**
	* Mark server `load` functions that call `fetch(url)` as depending on `url`, allowing you to
	* call `invalidate(url)` from the client. The URL, including e.g. sensitive query parameters,
	* will be visible to the client. This option will be removed in version 2; use `depends` instead
	*/
	trackServerFetches?: boolean;

[elliott-with-the-longest-name-on-github]

I dunno, I like explicitly requiring users to acknowledge what they're doing -- there's no guarantee they understand why this is dangerous. Happy to make the change, but I personally think the annoyance of typing a gigantic and explicit config value is worth it, especially since it's not going to be around forever.