20343 Dedupe sources for fuchsia shell/tests (cla: yes, platform-fuchsia)

20422 Fix broken shell_unittests on Fuchsia (affects: tests, cla: yes, platform-fuchsia)

20427 Add –unoptimized and –asan to Fuchsia builds (cla: yes, platform-fuchsia)

20486 Remove the dummy rasterizer delegate now that flutter_runner is in tree, and cleanup ctor params (cla: yes, platform-android, platform-fuchsia, platform-ios, waiting for tree to go green)

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

20638 Update view attributes after creation (affects: engine, cla: yes, platform-fuchsia, waiting for tree to go green)