68157 [NNBD] Migrate some Widgets tests (a: null-safety, a: tests, cla: yes, framework, team, waiting for tree to go green)

68160 Convert some more widget tests to NNBD (a: accessibility, cla: yes, framework, waiting for tree to go green)

68163 Migrate last batch of tests (cla: yes, framework, waiting for tree to go green)

68166 Rerun text formatters in didUpdateWidget if needed (cla: yes, framework, waiting for tree to go green)

68171 Make TabBar indicator color automatic adjustment optional (cla: yes, f: material design, framework, waiting for tree to go green)

68173 [NNBD] Migrate more widget tests to NNBD (a: accessibility, cla: yes, framework, waiting for tree to go green)