revert dev command default options

[bluwy]

fix #4947

Turns out setting the default host value to localhost, makes plain --host option be "" instead of true.

Reverting #4932 as there isn't a nice way to handle this. Re Vite port being 5173 in the future, I've made 3000 as the default port in the base config.

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[bluwy]

Hmm this isn't the right fix. If the --host option was never defined, and it defaults to localhost, we shouldn't override it if say, the port is configured in svelte.config.js (due to config merging). Was on oversight when adding the default values. Maybe we should revert #4932

EDIT: Issue addressed

[bluwy]

Pushed a commit to revert #4932. Sorry for the fuss!