41880 Clean up test infrastructure (cla: yes, team, tool)

41882 Increase template Swift version from 4 to 5 (cla: yes, d: examples, team, tool, ⌘‬ platform-mac, ⌺‬ platform-ios)

41885 Include embedding transitive dependencies in plugins (cla: yes, tool, waiting for tree to go green)

41889 Clean up ProjectFileInvalidator.findInvalidated a bit (cla: yes, tool)

41892 Fix CupertinoActivityIndicator radius (cla: yes, f: cupertino, framework)

41906 Ensure plugin registrants are generated in build_web (cla: yes, tool, ☸ platform-web)

41922 Enable more web tests; use blacklist to filter them out (a: tests, cla: yes, framework, team)