18308 [fuchsia] Disable failing physical shape layer tests ()

18313 Add FlKeyEventPlugin (cla: yes)

18314 Add FlTextInputPlugin (cla: yes)

18316 Add FlPlatformPlugin (cla: yes)

18317 1.18.0-11.1.pre: Update 1.18 engine hash to Dart 2.9.0-8.2.beta (cla: yes)

18319 Temporarily disabling the fuchsia runtime tests (cla: yes)

18320 Implement WriteAtomically using write/fsync on all platforms, and enable file unittests on Fuchsia (cla: yes, waiting for tree to go green)

18321 Set caches directory on Fuchsia (cla: yes)