Accurate merge properties with type file generation

[black7375]

Description

Generate types to improve type inference performance and automatically detect CSSMergeProperties. (Previously, all CSS properties were allowed to merge spaces and commas.)

It uses the same version of the mdn-data package as csstype.

Related RFC

• https://github.com/mincho-js/working-group/blob/main/text/000-css-literals.md#7-merge-values

Checklist

• [ ] Make merging only possible for properties that use space and comma, not all CSS properties