19981 Enabled linting on engine.cc (cla: yes)

19983 Make EncodableValue a thin std::variant wrapper (affects: engine, cla: yes, glfw, platform-windows)

19986 1.20.0 CP: Remove android view from the Mutator stack (#19972) (cla: yes, platform-android)

19987 This makes the lint script use multiprocessing to speed it up. (cla: yes)

19988 Fix lint errors in lib/ui (cla: yes)

19989 support fallback codecs on Windows, macOS, iOS (cla: yes, waiting for tree to go green)

19990 Lint fixes for fml, tools subdirs (cla: yes)

19991 Fix lint errors in vulkan directory. (cla: yes)