64665 [flutter_tools] reland: avoid creating Android Devices if AndroidSDK cannot be found (cla: yes, tool)

64671 Re-enable the Dart Development Service (DDS) (cla: yes, tool)

64674 Avoid thinning frameworks in iOS extensions (cla: yes, platform-ios, team, tool, waiting for tree to go green)

64737 Flutter Framework Beta 1.21.0-9.2.pre cherry picks (a: internationalization, cla: yes, engine, f: material design, framework, tool)

64745 [flutter_tools] rethrow process exceptions as tool exit from gradle build (cla: yes, tool, waiting for customer response)

64749 [flutter_tools] handle OsError thrown during azure detector (cla: yes, tool, waiting for tree to go green)