48908 Update Devicelab README with new dashboard information (cla: yes, team)

48912 Roll engine bc41ab513932..348805107fe1 (2 commits) (autoroller: commit, cla: yes)

48913 Grammar fix: “it’s” -> “its” (cla: yes, framework, waiting for tree to go green)

48915 Allow for cupertino modal popups to be dismissed with semantics (a: accessibility, cla: yes, d: examples, f: cupertino, framework, team, team: gallery, waiting for tree to go green)

48916 Fix concurrent modification error (cla: yes, tool, waiting for tree to go green)