19583 fuchsia: Enable most unittests (affects: tests, cla: yes, code health, platform-android, platform-fuchsia)

20532 Reland: “fuchsia: Remove dead code / break dependencies” (affects: engine, cla: yes, code health, platform-fuchsia)

20647 fuchsia: Convert legacy permutations to build flag (affects: engine, affects: tests, cla: yes, code health, platform-fuchsia)

severe: performance - 4 pull request(s)

20003 Reland: Avoid a copy in EncodeImage (cla: yes, perf: speed, severe: performance)

20142 Create root isolate asynchronously (cla: yes, perf: speed, severe: performance)

20466 Add a service protocol for raster cache memory (cla: yes, perf: memory, severe: performance)