Is your feature request related to a problem? Please describe.
Currently, icons from font-awesome, material design and the internal ones are available, but it would be quite nice to also be able to use other icon libraries like bootstrap icons.

Describe the solution you'd like
I noticed that there's an IconType.Custom option, but that seems to just get ignored when using it.
I haven't been able to have a look at the source code, but maybe when using the custom or a bootstrap option, one can specify which classes should be applied on an <i> element to build the requested icon.

Describe alternatives you've considered
I'm currently fine with using the ones available, but having more options is always good.