[css-fonts] Inconsistency between `monospace` and `ui-monospaced`

[AmeliaBR]

The new UI font keywords recently added to Fonts 4 includes ui-monospaced (note the "d" at the end). In contrast, the existing generic keyword is monospace (no "d").

There is already lots of potential for authoring confusion over whether to include the "d" at the end of monospace or not, because both terms are used interchangeably in typography (monospace font or monospaced font). I don't think it is helpful to have two keywords in CSS with different grammatical inflections, it will make it that much harder to remember which version is correct.

[ExE-Boss]

Let’s fix that before any browser ships this.

We don’t want yet another item to add to the ever expanding list of legacy CSSWG mistakes.

[litherum]

Whoops!! Yes, let’s fix this immediately

[litherum]

I think I should be able to just make the edit, since this is so new and has no implementations. I'm not sure it's worth bringing up on the call.