cue: deprecate Value.Elem and Value.Template
cue: deprecate Value.Elem and Value.Template

LookupPath now supports both use cases.

Change-Id: I3ba7ab32f24bda79a63331190a8351508c50658b
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/9348
Reviewed-by: CUE cueckoo <0f32a827c9a5f00281f936ac78b5ef3ba80a954c@gmail.com>
Reviewed-by: Paul Jolly <a027184a55211cd23e3f3094f1fdc728df5e0500@myitcv.org.uk>

cuelang/cue