Chore: refactor api/unstable_dev()'s types

[rozenmd]

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At the moment, unstable_dev takes an object of options, with the following type:

interface DevOptions {
	env?: string;
	ip?: string;
	port?: number;
	localProtocol?: "http" | "https";
	assets?: string;
	site?: string;
	siteInclude?: string[];
	siteExclude?: string[];
	nodeCompat?: boolean;
	experimentalEnableLocalPersistence?: boolean;
	_: (string | number)[]; //yargs wants this
	$0: string; //yargs wants this
}

Ideally, consumers of unstable_dev shouldn't have to know about yargs, so we should resolve whatever typescript problem that requires us to add _ and $0 into that interface.

Also, we should review whether we want to add or remove options from this list for the initial "stable" release of dev.