49987 Add Gamepad support for the activation action (cla: yes, framework, waiting for tree to go green)

49992 Docs (RenderObject): minor fix and link to more information (cla: yes, framework, waiting for tree to go green)

49993 Docs: provide Guidance for SingleChildRenderObjectWidget implementations (cla: yes, framework, waiting for tree to go green)

49994 Docs: provide Guidance for MultiChildRenderObjectWidget implementations (cla: yes, d: api docs, documentation, framework)

50017 [flutter_driver] document caveats with driver method (a: tests, cla: yes, framework, waiting for tree to go green)

50029 [flutter_tools] Fix crash on null Android apiVersion (cla: yes, tool, waiting for tree to go green)