pkg/tool/cli: Fix Ask task

At the moment the task is not being resolved as the `kind` field is used to
resolve legacy kinds. It is the only task that has only this field, and not an
`$id` field.

Signed-off-by: Scott Lewis-Kelly <slewiskelly@slewiskel.ly>
Change-Id: I42d7d0676dbbd0544a8356da3cb34a11642b1dbd
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/532738
Unity-Result: CUEcueckoo <cueckoo@cuelang.org>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Paul Jolly <paul@myitcv.io>

Author: slewiskelly

pkg/tool/cli/cli.cue

@@ -30,7 +30,7 @@ Print: {
 //         repsonse: bool
 //     })
 Ask: {
-	kind: "tool/cli.Ask"
+	$id: "tool/cli.Ask"
 
 	// prompt sends this message to the output.
 	prompt: string