message: chore: add to codeowners
  This is a very late response to issue which requested reviewers on certain plugins. Also added an entry for `cost-insights-*` since there is now a `cost-insights-common` package.
diff: @@ -35,6 +35,7 @@ yarn.lock @backstage/reviewers @backst
  /plugins/code-coverage @backstage/reviewers @alde @nissayeva
  /plugins/code-coverage-backend @backstage/reviewers @alde @nissayeva
  /plugins/cost-insights @backstage/reviewers @backstage/silver-lining
  +/plugins/cost-insights-* @backstage/reviewers @backstage/silver-lining
  /plugins/explore @backstage/reviewers @backstage/sda-se-reviewers
  /plugins/explore-react @backstage/reviewers @backstage/sda-se-reviewers
  /plugins/fossa @backstage/reviewers @backstage/sda-se-reviewers
  @@ -44,13 +45,15 @@ yarn.lock @backstage/reviewers @backst
  /plugins/ilert @backstage/reviewers @yacut
  /plugins/jenkins @backstage/reviewers @timja
  /plugins/jenkins-backend @backstage/reviewers @timja
  -/plugins/kafka @backstage/reviewers @nirga
  -/plugins/kafka-backend @backstage/reviewers @nirga
  +/plugins/kafka @backstage/reviewers @nirga @andrewthauer
  +/plugins/kafka-backend @backstage/reviewers @nirga @andrewthauer
  /plugins/kubernetes @backstage/reviewers @backstage/warpspeed
  /plugins/kubernetes-* @backstage/reviewers @backstage/warpspeed
  /plugins/newrelic-dashboard @backstage/reviewers @mufaddal7
  /plugins/playlist @backstage/reviewers @kuangp
  /plugins/playlist-* @backstage/reviewers @kuangp
  +/plugins/rollbar @backstage/reviewers @andrewthauer
  +/plugins/rollbar-backend @backstage/reviewers @andrewthauer
  /plugins/scaffolder-backend-module-rails @backstage/reviewers @angeliski
  /plugins/scaffolder-backend-module-yeoman @backstage/reviewers @pawelmitka
  /plugins/search @backstage/reviewers @backstage/techdocs-core
  