add driver test command to cirrus (firebase#1342)

This teaches Cirrus to run the new drive-examples command added in flutter/plugin_tools#29 on iOS and Android simulators.

I'm sharding the plugins tests more and requesting more powerful Linux VMs to ensure that the tests don't time out now that they're running simulators.

.cirrus.yml

@@ -2,8 +2,8 @@ task:
   use_compute_credits: $CIRRUS_USER_COLLABORATOR == 'true' && $CIRRUS_PR == ''
   container:
     dockerfile: .ci/Dockerfile
-    cpu: 4
-    memory: 8G
+    cpu: 8
+    memory: 16G
   upgrade_script:
     - flutter channel master
     - flutter upgrade
@@ -22,11 +22,16 @@ task:
       test_script: ./script/incremental_build.sh test
     - name: analyze
       script: ./script/incremental_build.sh analyze
-    - name: build-apks+java-test
+    - name: build-apks+java-test+drive-examples
       env:
         matrix:
           PLUGIN_SHARDING: "--shardIndex 0 --shardCount 2"
           PLUGIN_SHARDING: "--shardIndex 1 --shardCount 2"
+      create_device_script:
+        echo no | avdmanager -v create avd -n test -k "system-images;android-21;default;armeabi-v7a"
+      start_emulator_background_script:
+      - $ANDROID_HOME/emulator/emulator -avd test -no-audio -no-window
+      wait_for_emulator_script: adb wait-for-device
       script:
         # Unsetting CIRRUS_CHANGE_MESSAGE and CIRRUS_COMMIT_MESSAGE as they
         # might include non-ASCII characters which makes Gradle crash.
@@ -40,19 +45,22 @@ task:
         - export CIRRUS_COMMIT_MESSAGE=""
         - ./script/incremental_build.sh build-examples --apk
         - ./script/incremental_build.sh java-test  # must come after apk build
+        - ./script/incremental_build.sh drive-examples
         - export CIRRUS_CHANGE_MESSAGE=`cat /tmp/cirrus_change_message.txt`
         - export CIRRUS_COMMIT_MESSAGE=`cat /tmp/cirrus_commit_message.txt`
 
 task:
   use_compute_credits: $CIRRUS_USER_COLLABORATOR == 'true'
-  name: build-ipas
+  name: build-ipas+drive-examples
   osx_instance:
     image: mojave-xcode-10.1
   env:
     PATH: $PATH:/usr/local/bin
     matrix:
-      PLUGIN_SHARDING: "--shardIndex 0 --shardCount 2"
-      PLUGIN_SHARDING: "--shardIndex 1 --shardCount 2"
+      PLUGIN_SHARDING: "--shardIndex 0 --shardCount 4"
+      PLUGIN_SHARDING: "--shardIndex 1 --shardCount 4"
+      PLUGIN_SHARDING: "--shardIndex 2 --shardCount 4"
+      PLUGIN_SHARDING: "--shardIndex 3 --shardCount 4"
   setup_script:
     - brew update
     - brew install libimobiledevice
@@ -64,6 +72,8 @@ task:
     - export PATH=`pwd`/flutter/bin:`pwd`/flutter/bin/cache/dart-sdk/bin:$PATH
     - flutter doctor
     - pub global activate flutter_plugin_tools
+    - xcrun simctl create Flutter-iPhone com.apple.CoreSimulator.SimDeviceType.iPhone-X com.apple.CoreSimulator.SimRuntime.iOS-12-1 | xargs xcrun simctl boot
   build_script:
     - export PATH=`pwd`/flutter/bin:`pwd`/flutter/bin/cache/dart-sdk/bin:$PATH
     - ./script/incremental_build.sh build-examples --ipa
+    - ./script/incremental_build.sh drive-examples