chore(create-vite): update reference to volar vscode extension

[nhedger]

Description

When scaffolding a new project with npm create vite@latest my-vue-app -- --template vue-ts or npm create vite@latest my-vue-app -- --template vue, opening the project within Visual Studio Code will trigger the following warning because the namespace for the Volar extension moved from johnsoncodehk.volar to Vue.volar. This PR updates the reference to fix the issue. It also updates the references in the README files.

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.