CSS LSP "@property" warns about unknown at-rule

[tomrav]

Actual Behavior

@property is currently not recognized by the CSS language service (probably because it is still experimental).

We have already adopted the syntax for our global declaration (@property st-global(--imGlobal)) and recommend it as an alternative to the now deprecated @st-global-custom-property --imGlobal; directive.

Expected Behavior

Should not warn (..and ideally, later, offer proper suggestions too).

Version

@stylable/language-service@4.8.0 (latest)

[tomrav]

similar to #1686