Changes to Links template and page

the request property layout became required

added the new optional request property layout/body/rows/items/columns/items/metadata

added the new optional request property layout/body/rows/items/metadata

added the new optional request property layout/bodyRows/items/columns/items/metadata

added the new optional request property layout/bodyRows/items/metadata

added the optional property entity/containers to the response with the 200 status

added the optional property entity/containersMap to the response with the 200 status

added the optional property entity/layout to the response with the 200 status

added the optional property entity/live to the response with the 200 status

added the optional property entity/numberContents to the response with the 200 status

added the optional property entity/page to the response with the 200 status

added the optional property entity/pageUrlMapper to the response with the 200 status

added the optional property entity/runningExperiment to the response with the 200 status

added the optional property entity/site to the response with the 200 status

added the optional property entity/styleEditorSchemas to the response with the 200 status

added the optional property entity/template to the response with the 200 status

added the optional property entity/urlContent to the response with the 200 status

added the optional property entity/vanityUrl to the response with the 200 status

added the optional property entity/viewAs to the response with the 200 status