Feature request: Add `<b></b>` tags if the text is already bold.

[sampajano]

Hi! Thanks so much for the plugin!

I frequently have text both bolded and underlined previously. So I wonder if it'd be possible to detect text such as **bold text** and when in that case, replace the text with <u><b>bold text</b></u>? It would be very helpful if so!

Thanks a lot for consideration! :)

[Benature]

I cannot quite get the motivation. In my case, <u>**test**</u> is alright in preview.