Adds a Linux Fuchsia FEMU config that enables CSO (flutter/engine#39718)

* Adds a Linux Fuchsia FEMU config that enables CSO

* Update .ci.yaml

* Update .ci.yaml

engine/src/flutter/.ci.yaml

@@ -156,6 +156,19 @@ targets:
       emulator_arch: "x64"
     timeout: 60
 
+  - name: Linux Fuchsia FEMU (cso)
+    recipe: engine/femu_test
+    bringup: true
+    properties:
+      add_recipes_cq: "false"
+      build_fuchsia: "true"
+      fuchsia_ctl_version: version:0.0.27
+      # ensure files from pre-production Fuchsia SDK tests are purged from cache
+      clobber: "true"
+      emulator_arch: "x64"
+      enable_cso: "true"
+    timeout: 90
+
   - name: Linux Fuchsia arm64 FEMU
     recipe: engine/femu_test
     bringup: true