[Feature Request] Add default classNames on provider

[dexcell]

Usage example, including component/hook API

So people can add tailwind or css utility classes to override/add button className by default

Possible implementation – describe how the feature can be implemented

<MantineProvider
      classNames={{ Button: { root: 'font-medium bg-red-500' } }}
    >

Do you want to contribute this feature and create a pull request

No

[frec-hansen]

#912