VSCode does not highlight given in import list

[odersky]

The new given import is like this:

import a.b.given
import a.b.{_, given}
import a.b.{given X}

Currently VSCode does not syntax-highlight the given in these positions.

[nicolasstucki]

[nicolasstucki]

@odersky could you have a look at scala/vscode-scala-syntax#56