Migrate to wxt and mv3

[qiweiii]

pr: https://github.com/qiweiii/markdown-sticky-notes/pull/43

Manifest version 3 migration is block by a content script problem:

• Some dependencies(probably @uiw/react-codemirror and related packages) in Note.tsx contain non utf8 characters, and browser content-script does not allow that.

• A solution is to use another code-mirror alternative, but I cannot find a good one with all the themes we already provide, and to make the extension backwards compatible, I want to keep all the themes. There is a @uiw/react-md-editor looks good, but also have utf8 problem.

• Another solution is to use iframe as suggested in this issue, but in my use case, I cannot use iframe as the root for all sticky notes, that will make parent window not usable. If I use an iframe for each created note, it's hard to impl and may make browser laggy.

• A third solution is to replace/remove all no-utf8 characters, I tried to use a custom vite plugin, there are some characters that are easy to replace, but others are not easy to do so, coz it will affect runtime logic and cause runtime errors.

[qiweiii]

Following the latest solution in https://github.com/wxt-dev/wxt/issues/353 works, using a custom vite plugin!

[qiweiii]

TODO

• [x] migrate to mv3 (so this extension won't be disabled by chrome)
• [x] make old features work with wxt
• [x] clean the code