57345 Protect the deletion of the local engine temp dir in case it is alrea… (cla: yes, tool, waiting for tree to go green)

57349 Device manager choose running device (cla: yes, tool, waiting for tree to go green)

57355 [flutter tools] Improve messages when we fail to connect to the Observatory (cla: yes, tool, waiting for tree to go green)

57392 [flutter_tools] check for Runner.sln when parsing for plugins (cla: yes, tool)

57400 [flutter_tools] handle missing null check in manifest parser (cla: yes, tool)

57402 Roll engine aaf9e79f1d29..2bd71fb60a43 (52 commits) (cla: yes, waiting for tree to go green)