chore(types): inject plugin types

[Yizack]

📚 Description

This PR adds plugin type declaration injection, this also to enables ctrl+click to open $cookies definition when used with the useNuxtApp composable. I've seen other modules type their plugins this way too.

Injecting plugin types also avoids unknown types on vue-tsc checks.

• Reference: https://nuxt.com/docs/guide/directory-structure/plugins#typing-plugins

Solves ci errors on #220

📝 Checklist

• [x] All commits follow the Conventional Commit format
• [x] The PR's title follows the Conventional Commit format

[dargmuesli-bot]

:tada: This PR is included in version 8.4.4 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: