chore: simplify <select> initialization

[Rich-Harris]

Follow-up to #16250. There's a lot of unnecessary dancing around with <select> values that we can solve by being smarter about the order in which things happen — if we initialize the child <option> values first, we don't need to muck about passing the value into the init_select function that sets up the MutationObserver.

This, in turn, will allow us to get rid of the special handling of that attribute, but I'll do that as a follow-up. changed my mind

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Playground

pnpm add https://pkg.pr.new/svelte@16251

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Preview: https://svelte-dev-git-preview-svelte-16251-svelte.vercel.app/

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

LGTM