Add "unit-disallowed-list": "%" to config

[Volker-E]

Consider settling on ems only for relative font-sizing, not ending up with using both. We could also add ex to disallowed list in same activity.

[jdforrester]

I'm also OK with this.

[Volker-E]

"unit-blacklist": [
	"%",
	"rem"
]

is not a universal solution with box-sizing properties needing to feature %. It should be considered to be added in a follow-up to #105 for font-size instead.

[jdlrobson]

Does this issue include adding support for rems? If not, I'll open a new ticket, but we're likely be used rems soon as part o the font-size changes in Vector 2022 (https://phabricator.wikimedia.org/T261334.)

[jdforrester]

Does this issue include adding support for rems? If not, I'll open a new ticket, but we're likely be used rems soon as part o the font-size changes in Vector 2022 (https://phabricator.wikimedia.org/T261334.)

Let's do that as a related task; this one needs re-thinking, as adding % directly to unit-disallowed-list will break color: lighten( #fc0, 50% ); (from our test suite).