[WebView Support Library] initial demo app

This adds an initial demo app. This is a ListView which points to other
Activities (each of which may similarly point to other Activities, or
may actually exercise a feature).

So far, none of these activities exercise any WebView features, other
than the MainActivity which adds the WebView version to its title (using
WebViewCompat#getCurrentWebViewPackage).

This creates an empty SafeBrowsingActivity for the sake of populating
the top-level ListView with something. We'll later populate
SafeBrowsingActivity with a similar ListView for each specific Safe
Browsing edge case.

Bug: 78154299
Test: ./gradlew :webkit-demos:assembleDebug :webkit-demos:installDebug \
    && adb shell monkey -p "com.example.androidx.webkit" \
    -c android.intent.category.LAUNCHER 1

Change-Id: I67724ff344d96b2576366f039591a22dd4c1eb3b
diff --git a/settings.gradle b/settings.gradle
index b30d1ed..1a79149 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -171,6 +171,7 @@
 includeProject(":viewpager2", "viewpager2")
 includeProject(":wear", "wear")
 includeProject(":webkit", "webkit")
+includeProject(":webkit:integration-tests:testapp", "webkit/integration-tests/testapp")
 includeProject(":work:work-runtime", "work/workmanager")
 includeProject(":work:work-runtime-ktx", "work/workmanager-ktx")
 includeProject(":work:work-firebase", "work/workmanager-firebase")