Fix CIDER formatting buttons on Safari

[germain-gg]

Hi folks 👋 ,

This PR fixes element-hq/element-web#15710

The issue stemmed from the fact that document.getSelection() would be empty when called inside BasicMessageComposer.tsx#onFormatAction.
After a bit of digging around it appears that Safari resets the selection if a user clicks on something different than a <button type="button"> (which is odd given that passing the role="button" attribute down should help)

My fix is to essentially use the more semantic HTML tag. I had a bit of CSS tweaking as button inherit a background colour and have a different inline type compared to div.
There are references to an as prop on the AccessibleButton component but could not see it anywhere in the proptypes, I have assumed that element was the appropriate prop to use here

PS: I have updated docs where names have gone stale after migrating from JS to TS

[t3chguy]

Good catch on the Safari specific weirdness

LGTM