add wrap() for Vue3

[TatsuyaYamamoto]

@LinusBorg
I'm sorry to mention you suddenly.
I want use vue-web-component-wrapper for Vue3 so I opened this draft PR.

I'm aware that @LinusBorg started working on this porting (#93#issuecomment-751347772) and this task is a bit lower priority (93#issuecomment-778991647) .

I understand it takes time to develop some great features, but I want you to provided wrap() for v3 providing the same functions as the current one first. So, I opened this.

This PR is draft so wrap() for v3 is not implemented yet. After @LinusBorg accept this PR's policy, I'll resume to work on remaining tasks.

Summary of fixes

• implements 2 wrap functions for v2 and v3.
  • wrapV2
    • The implementation is the same as src/index.js. The filename is different only.
  • wrapV3
    • The implementation is for Vue3.
• keep spec and switch between v2 and v3 internally. (src/index.ts)
  • I'm aware that vue-cli depends on vue-web-component-wrapper so it will take time before it can be used with vue-cli if I change api spec.
  • wrap() in new entry function (src/index.ts) has the same parameters as the current entry function.
  • switch between wrapV2() and wrapV3() according to Vue.version.

Files

• src/index.ts
  • new entry file
• src/wrapV2.js, src/wrapV3.ts
  • actual function for V2 and V3.
• rollup.config.js, tsconfig.json, dist/index.d.ts, (deleted) types/index.d.ts
  • src/index.ts and src/wrapV3.ts is written by TypeScript and rollup plugin transpiles them.
  • when transpiling, tsc emit declaration file (dist/index.d.ts)
• test/fixtures/*.html
  • test/fixtures/*.html load transpilede code.

[TatsuyaYamamoto]

Vue 3.2 has built-in support for web component wrappers so I close this PR.
https://v3.vuejs.org/guide/web-components.html

[sherlock1982]

Unfortunately it is seriously different from this component wrapper.

<style module> is not supported for root web component. <style module> in child component is being added to the instead of shadowRoot.

[LinusBorg]

There's ongoing work in that general direction here:

vuejs/core#4309