Support for plugin-react

[thcrt]

In development environments, a script needs to be added to pages that looks like this:

<script type="module">
    import RefreshRuntime from 'http://localhost:3000/@react-refresh'
    RefreshRuntime.injectIntoGlobalHook(window)
    window.$RefreshReg$ = () => {}
    window.$RefreshSig$ = () => (type) => type
    window.__vite_plugin_react_preamble_installed__ = true
</script>

(source)

It would be good if flask-vite were to include this when calling {{ vite_tags() }} in development environments. In production, this shouldn't be necessary.