Add an e2e (host-independent) test demo to testing_app (#515)

testing_app/pubspec.lock

@@ -7,14 +7,14 @@ packages:
       name: _fe_analyzer_shared
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "4.0.0"
+    version: "7.0.0"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.39.10"
+    version: "0.39.17"
   archive:
     dependency: transitive
     description:
@@ -50,6 +50,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.1.3"
+  cli_util:
+    dependency: transitive
+    description:
+      name: cli_util
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.2.0"
   collection:
     dependency: transitive
     description:
@@ -84,7 +91,7 @@ packages:
       name: csslib
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.16.1"
+    version: "0.16.2"
   cupertino_icons:
     dependency: "direct main"
     description:
@@ -92,6 +99,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.1.3"
+  e2e:
+    dependency: "direct dev"
+    description:
+      name: e2e
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.7.0"
   file:
     dependency: transitive
     description:
@@ -139,7 +153,7 @@ packages:
       name: http
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.1"
+    version: "0.12.2"
   http_multi_server:
     dependency: transitive
     description:
@@ -216,7 +230,7 @@ packages:
       name: mime
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.9.6+3"
+    version: "0.9.7"
   multi_server_socket:
     dependency: transitive
     description:
@@ -307,7 +321,7 @@ packages:
       name: provider
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "4.1.3"
+    version: "4.3.2"
   pub_semver:
     dependency: transitive
     description:
@@ -328,7 +342,7 @@ packages:
       name: shelf
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.7.7"
+    version: "0.7.8"
   shelf_packages_handler:
     dependency: transitive
     description:
@@ -452,7 +466,7 @@ packages:
       name: vm_service
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "4.1.0"
+    version: "4.2.0"
   vm_service_client:
     dependency: transitive
     description:
@@ -504,4 +518,4 @@ packages:
     version: "2.2.1"
 sdks:
   dart: ">=2.7.0 <3.0.0"
-  flutter: ">=1.16.0"
+  flutter: ">=1.16.0 <2.0.0"