72162 Make web buttons respond to enter key (cla: yes, f: material design, framework, waiting for tree to go green)

72163 Add some new examples to Actions and Shortcuts (cla: yes, f: material design, framework)

72166 [devicelab] Migrate web_benchmarks_canvaskit to LUCI (cla: yes, team, waiting for tree to go green)

72169 Migrate the first batch of API samples to null safety (a: accessibility, cla: yes, framework, team, waiting for tree to go green)

72189 [flutter_tools] use 1-based index for device selection (cla: yes, tool, waiting for tree to go green)

72196 [flutter_tools] improve error surfacing from Linux builds (cla: yes, tool, waiting for tree to go green)