Setup users host env for local instance support

- Setup flow controller in setup.py
- Define common method in base_task_runner.py
- Required package installer in host_setup_runner.py
- Host env configuration in host_setup_runner.py

Bug: 110388133
Test: ./run_tests.sh, m acloud && acloud setup.
Change-Id: Id8b988149d606553d31dfb466e0ae14883513553
diff --git a/internal/constants.py b/internal/constants.py
index 78b0294..7367ef2 100755
--- a/internal/constants.py
+++ b/internal/constants.py
@@ -13,7 +13,6 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
 """This module holds constants used by the driver."""
 BRANCH_PREFIX = "git_"
 BUILD_TARGET_MAPPING = {
@@ -22,8 +21,9 @@
     "aosp_phone": "aosp_cf_x86_phone-userdebug",
     "aosp_tablet": "aosp_cf_x86_tablet-userdebug",
 }
-SPEC_NAMES = {"nexus5", "nexus6", "nexus7_2012", "nexus7_2013", "nexus9",
-              "nexus10"}
+SPEC_NAMES = {
+    "nexus5", "nexus6", "nexus7_2012", "nexus7_2013", "nexus9", "nexus10"
+}
 
 DEFAULT_SERIAL_PORT = 1
 LOGCAT_SERIAL_PORT = 2
@@ -32,3 +32,5 @@
 TYPE_GCE = "gce"
 TYPE_CF = "cuttlefish"
 TYPE_GF = "goldfish"
+
+USER_ANSWER_YES = {"y", "yes", "Y"}