This change uses go/types information to get the types for the
different symbols. It also groups the symbols according to their kinds,
though this doesn't seem to be reflected in the actual VSCode UI...
Updates golang/go#30915
Change-Id: I2caefe01f9834aaad6b9e81cd391d461405ef725
Reviewed-on: https://go-review.googlesource.com/c/tools/+/169438
Reviewed-by: Ian Cottrell <iancottrell@google.com>