26408 Add Handle.replace(int rights). (cla: yes, platform-fuchsia)

26422 fuchsia: Delete all the legacy code! (cla: yes, Work in progress (WIP), platform-web, platform-fuchsia, tech-debt)

26426 Canonicalize runner debug symbol path for fuchsia. (cla: yes, waiting for tree to go green, platform-fuchsia)

26453 Add todo to handle_test. (cla: yes, waiting for tree to go green, platform-fuchsia)

26463 Add debug symbols (symbol-index) to serve.sh for Fuchsia. (cla: yes, waiting for tree to go green, platform-fuchsia)

26506 Cache Handle.koid(). (cla: yes, waiting for tree to go green, platform-fuchsia)