DO NOT MERGE: AGP integration test.

This detects the problem of #7769.

To actually merge this, I'd want to:

- Make it work with the version of Gradle we already use, 8.5, or else
  upgrade the somewhat-standard version of Gradle that's used across a
  handful of Google project, including ours.

- Integrate it into our CI and release processes, including testing with
  the version that we're building, as [in our Gradle integration tests
  for our module
  metadata](https://github.com/google/guava/blob/97c96e00bd8940b45399979cbd4162d3ef362532/integration-tests/gradle/build.gradle.kts#L1).

- Maybe put some patterns into `.gitignore`, as possibly I should have
  along with the previous Gradle integraiotn tests?

Author: cpovirk

integration-tests/agp/app/build.gradle.kts

@@ -0,0 +1,22 @@
+plugins {
+  id("com.android.application")
+  id("org.jetbrains.kotlin.android")
+}
+
+android {
+  namespace = "com.google.guava.agptest"
+
+  compileSdk = 35
+
+  defaultConfig {
+    applicationId = "com.google.guava.agptest"
+    minSdk = 21
+    targetSdk = 35
+    versionCode = 1
+    versionName = "1.0"
+  }
+}
+
+dependencies {
+  implementation("com.google.guava:guava:999.0.0-HEAD-android-SNAPSHOT")
+}

integration-tests/agp/app/src/main/AndroidManifest.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+  <uses-sdk android:minSdkVersion="21" />
+</manifest>

integration-tests/agp/build.gradle.kts

@@ -0,0 +1,4 @@
+plugins {
+  id("com.android.application") version "8.9.0" apply false
+  id("org.jetbrains.kotlin.android") version "2.1.10" apply false
+}

integration-tests/agp/gradle/wrapper/gradle-wrapper.jar

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.11.1-all.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists