22194 [iOS] Fixes DisplayLinkManager leaks (cla: yes, platform-ios)

22206 [ios] Surface factory holds the canonical reference to the external view embedder (cla: yes, platform-ios)

22214 Platform views have CreateExternalViewEmbedder (cla: yes, platform-android, platform-ios, waiting for tree to go green)

22227 Fix includes to start with shell (cla: yes, platform-ios)

22272 Remove GetExternalViewEmbedder from surface (cla: yes, platform-android, platform-ios, waiting for tree to go green)

22275 Do not involve external_view_embedder in submit frame process if threads are not merged. (cla: yes, platform-ios, waiting for tree to go green)