Option for fontawesome icons instead of octicon for dropdowns

[nyoma-diamond]

Context

A number of popular themes, particularly the PyData theme and sphinx-book-theme, use Fontawesome to provide icons for admonitions. As a result, using Octicon for dropdown icons conflicts stylistically due to not supporting Fontawesome icons.

Proposal

It would be convenient to have the additional ability to use Fontawesome icons for consistency with themes that use them for admonitions.

Tasks and updates

No response