[Change Proposal] Add "search" to validate_visualizations_used_by_value

[kertal]

@davismcphee of @elastic/kibana-data-discovery recently added support for By value searches in elastic/kibana#148995

With this, search should be added to warn the authors if they are using by-reference saved searches, which done in this part of the code:

package-spec/code/go/internal/validator/semantic/validate_visualizations_used_by_value.go

Line 86 in 1cea521

case "lens", "visualization", "map":

This makes sure by-value saved searches become the preferred way of using saved searches in our integrations