Add plumbing for changing the CMake version.

The value I've set here is no different from the default, but soon it
will be (hopefully), and this makes it easier to test a newer CMake.

build-logic/src/main/java/com/android/ndk/samples/buildlogic/AndroidApplicationConventionPlugin.kt

@@ -16,6 +16,13 @@ class AndroidApplicationConventionPlugin : Plugin<Project> {
             extensions.configure<ApplicationExtension> {
                 compileSdk = Versions.COMPILE_SDK
                 ndkVersion = Versions.NDK
+
+                externalNativeBuild {
+                    cmake {
+                        version = Versions.CMAKE
+                    }
+                }
+
                 defaultConfig {
                     minSdk = Versions.MIN_SDK
                     targetSdk = Versions.TARGET_SDK

build-logic/src/main/java/com/android/ndk/samples/buildlogic/AndroidLibraryConventionPlugin.kt

@@ -15,6 +15,13 @@ class AndroidLibraryConventionPlugin : Plugin<Project> {
             extensions.configure<LibraryExtension> {
                 compileSdk = Versions.COMPILE_SDK
                 ndkVersion = Versions.NDK
+
+                externalNativeBuild {
+                    cmake {
+                        version = Versions.CMAKE
+                    }
+                }
+
                 defaultConfig {
                     minSdk = Versions.MIN_SDK
                     lint {

build-logic/src/main/java/com/android/ndk/samples/buildlogic/Versions.kt

@@ -7,5 +7,6 @@ object Versions {
     const val TARGET_SDK = 34
     const val MIN_SDK = 21
     const val NDK = "27.1.12297006" // r27b
+    const val CMAKE = "3.22.1"
     val JAVA = JavaVersion.VERSION_1_8
 }