80168 Migrate features_tests and other tool tests to null safety (team, tool, cla: yes, waiting for tree to go green, a: null-safety)

80304 Migrate flutter_tool plugins.dart to null safety (team, tool, cla: yes, waiting for tree to go green, a: null-safety)

80320 Migrate reporting library to null safety (team, tool, cla: yes, waiting for tree to go green, a: null-safety)

80324 Pull XCDevice out of xcode.dart (team, tool, cla: yes, waiting for tree to go green, a: null-safety)

80392 Migrate flutter_manifest to null safety (team, tool, cla: yes, waiting for tree to go green, a: null-safety)