feat(compiler-sfc): ignore empty blocks

[cexbrayat]

The current implementation ignores <script/> and <styles/> but not empty blocks like <script> \n\t</script>.
This results in unnecessary code generated for a component when these blocks are actually empty.

This commit filters such nodes in the SFC compiler, resulting in less code generated.

For example, this component:

<template>
  <h1>{{ msg }}</h1>
</template>

<script setup>

</script>

<style scoped>
  
</style>

currently produces:

/* Analyzed bindings: {} */
import { toDisplayString as _toDisplayString, openBlock as _openBlock, createBlock as _createBlock, withScopeId as _withScopeId } from "vue"
const _withId = /*#__PURE__*/_withScopeId("data-v-f13b4d11")


const __sfc__ = {
  expose: [],
  setup(__props) {



return /*#__PURE__*/_withId((_ctx, _cache) => {
  return (_openBlock(), _createBlock("h1", null, _toDisplayString(_ctx.msg), 1 /* TEXT */))
})
}

}
__sfc__.__scopeId = "data-v-f13b4d11"
__sfc__.__file = "App.vue"
export default __sfc__

(see https://sfc.vuejs.org/#eyJBcHAudnVlIjoiPHRlbXBsYXRlPlxuICA8aDE+e3sgbXNnIH19PC9oMT5cbjwvdGVtcGxhdGU+XG5cbjxzY3JpcHQgc2V0dXA+XG5cbjwvc2NyaXB0PlxuXG48c3R5bGUgc2NvcGVkPlxuXG48L3N0eWxlPiJ9)

With this commit, it produces:

const __sfc__ = {}
import { toDisplayString as _toDisplayString, openBlock as _openBlock, createBlock as _createBlock } from "vue"
function render(_ctx, _cache) {
  return (_openBlock(), _createBlock("h1", null, _toDisplayString(_ctx.msg), 1 /* TEXT */))
}
__sfc__.render = render
__sfc__.__file = "App.vue"
export default __sfc__