Add theme manager to provide and consume styles

[Saul-Mirone]

Theme Manager

Add a theme manager to provide and consume styles.

Usage

With Class Nodes

export const ThemeKey = createThemeProviderKey<{ level: number }>("heading")
export type ThemeKeyType = typeof ThemeKey;
export const heading = createNode<Keys>((utils) => {
    utils.themeManager.inject(ThemeKey);
    return {
        id,
        schema: () => ({
            content: 'inline*',
            toDOM: (node) => [`h{node.attrs.level}`, { class: utils.themeManager.get(ThemeKey, { level: 1 }) }]
            // ...
        }),
    };
});

With Theme

export const theme = themeFactory((emotion, manager) => ({
  // ...
  manager.setCustom<ThemeKeyType>('heading', ({ level }) =>
        return emotion.css`...`
  })
}))

[tantaman]

Thanks for doing this!