65426 [flutter_tools] remove advice about running sdkmanager directly in favor of directing to flutter.dev (cla: yes, tool, waiting for tree to go green)

65435 [flutter_tools] alternate the name of the dill file used for hot restart (cla: yes, tool)

65490 [flutter_tools] remove globals from tracing and add unit tests (cla: yes, tool, waiting for tree to go green)

65493 Always use POSIX paths for generated CMake files (cla: yes, tool)

65511 Update Windows app template (cla: yes, tool, waiting for tree to go green)

65571 Roll forward package:test to 1.16.0-nullsafety.4 to prepare for package:vm_service 5.0.0+1 (cla: yes, team, tool, waiting for tree to go green)