fix(`@vtmn/svelte`): fix dispatch close for `VtmnAlertItem` / `VtmnSnackbarItem` / `VtmnToastItem`

[Tlahey]

Changes description

The close dispatch is send even if the user has set a timeout to 0. This PR fix this behaviour.

Context

Checklist

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• [x] I have reviewed the submitted code.
• [x] I have tested on related showcases.
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Does this introduce a breaking change?

• No

Other information