Don’t add spaces around raw / that are preceded by numbers

[thecrypticace]

We would previously add spaces around slashes that were preceded by numbers (with a few other constraints) but these are not necessary. In CSS slashes don't need to have spaces around them because they're tokenized such that whitespace is insignificant.

This was a problem for plugins that used file paths as raw values without quotes. We would see foo-[/foo/bar-2/baz.png] and normalize the raw value internally by turning this into /foo/bar-2 / baz.png and passing that as the value given to matchUtilities.

We already limited adding spaces around operators to when using min/max/clamp/calc/etc… in #8091 but kept the spaces around slashes explicitly as to cause less churn for utilities like aspect ratio. There shouldn't be any reason we actually need to keep them though so this change seems fine.

Fixes #8661