adds lens as a readable saved object for read-only dashboard users

Author: legrego

x-pack/plugins/features/server/__snapshots__/oss_features.test.ts.snap

@@ -172,6 +172,7 @@ export const buildOSSFeatures = ({ savedObjectTypes, includeTimelion }: BuildOSS
               'visualization',
               'timelion-sheet',
               'canvas-workpad',
+              'lens',
               'map',
               'dashboard',
               'query',