Compose HTML: add `StyleScope.inset` extension functions

[ShreckYe]

From https://developer.mozilla.org/en-US/docs/Web/CSS/inset:

The inset CSS property is a shorthand that corresponds to the top, right, bottom, and/or left properties.

Testing

I didn't add tests yet as I see there are no tests for the existing inset functions such as StyleScope.top.

Release Notes

Features - HTML library

• Add StyleScope.inset extension functions