62368 [roll] roll to 2.10 (cla: yes, engine, team, tool)

62372 Parse .flutter-plugins-dependencies for add-to-app iOS modules, remove no-op plugin iOS folder (a: existing-apps, cla: yes, platform-ios, team, tool)

62395 [gen_l10n] Synthetic package generation by default (a: internationalization, cla: yes, severe: API break, team, tool, waiting for tree to go green)

62426 [flutter_tools] ensure desktop builds can run without flutter_tools’ package_config (cla: yes, tool, waiting for tree to go green)

62444 1.20.0-7.3.pre beta cherrypicks (CQ+1, cla: yes, engine, tool)