Dark theme based on body class

[kickthemooon]

Clear and concise description of the problem

As a developer using Naive UI I want to be able to toggle the dark/light theme based on a class on the body so that I don't have to introduce other more specific implementations.

Suggested solution

Provide a way to configure Naive UI so that it is dark/light based on a class on the html body e.g. "dark".

Alternative

No response

Additional context

No response

Validations

• [X] Read the Contributing Guidelines.
• [X] Read the docs.
• [X] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[skamansam]

I would also like this feature, in order to be more compatible with tailwind.