refactor: don't inject Lumo theme globally

[sissbruecker]

Removes injecting the docs example styles globally. This should make it possible to switch between the Aura and Lumo theme in examples. For now some Lumo props and global style rules for the Lumo dark theme are still injected globally to keep examples working.

[github-actions]

AI Language Review

• The imported Lumo icon font and Lumo color props have been added for global use in examples rendering with the Lumo theme. Ensure these imports are necessary and correctly applied, as they increase the external resources fetched.
• In the applyTheme function, there's a new condition to return early if root equals document. Make sure this condition is appropriate and does not inadvertently prevent required theming for certain components.
• Ensure that the change to reset the theme application for the document does not negatively impact the functionality for scenarios where it might be necessary.
• Check consistency and impact of this change in environments where the document's theme is necessary.
• Consider any potential side effects of these added imports and changes in different environments or build configurations, as they may introduce unexpected behaviors or dependencies.