Centralise the DI code generation logic (#3562)

* Create Anvil extension helper

* Use the helper everywhere

plugins/src/main/kotlin/extension/AnvilExtensions.kt

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2024 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ * Please see LICENSE in the repository root for full details.
+ */
+
+package extension
+
+import com.squareup.anvil.plugin.AnvilExtension
+import org.gradle.accessors.dm.LibrariesForLibs
+import org.gradle.api.Project
+import org.gradle.api.provider.Provider
+import org.gradle.kotlin.dsl.the
+import org.gradle.plugin.use.PluginDependency
+
+/**
+ * Setup Anvil plugin with the given configuration.
+ * @param generateDaggerCode whether to enable general Dagger code generation using Kapt
+ * @param generateDaggerFactoriesUsingAnvil whether to generate Dagger factories using Anvil instead of Kapt
+ */
+fun Project.setupAnvil(
+    generateDaggerCode: Boolean = false,
+    generateDaggerFactoriesUsingAnvil: Boolean = true,
+) {
+    val libs = the<LibrariesForLibs>()
+    // Apply plugins and dependencies
+    applyPluginIfNeeded(libs.plugins.anvil)
+
+    if (generateDaggerCode) {
+        applyPluginIfNeeded(libs.plugins.kapt)
+        // Needed at the top level since dagger code should be generated at a single point for performance
+        dependencies.implementation(libs.dagger)
+        dependencies.add("kapt", libs.dagger.compiler)
+    }
+
+    // These dependencies are only needed for compose library or application modules
+    if (project.pluginManager.hasPlugin("io.element.android-compose-library")
+        || project.pluginManager.hasPlugin("io.element.android-compose-application")) {
+        // Annotations to generate DI code for Appyx nodes
+        dependencies.implementation(project.project(":anvilannotations"))
+        // Code generator for the annotations above
+        dependencies.add("anvil", project.project(":anvilcodegen"))
+    }
+
+    project.pluginManager.withPlugin(libs.plugins.anvil.get().pluginId) {
+        // Setup extension
+        extensions.configure(AnvilExtension::class.java) {
+            this.generateDaggerFactories.set(generateDaggerFactoriesUsingAnvil)
+        }
+    }
+}
+
+private fun Project.applyPluginIfNeeded(plugin: Provider<PluginDependency>) {
+    val pluginId = plugin.get().pluginId
+    if (!pluginManager.hasPlugin(pluginId)) {
+        pluginManager.apply(pluginId)
+    }
+}

plugins/src/main/kotlin/extension/DependencyHandleScope.kt

@@ -12,6 +12,7 @@ import ModulesConfig
 import org.gradle.accessors.dm.LibrariesForLibs
 import org.gradle.api.Action
 import org.gradle.api.artifacts.ExternalModuleDependency
+import org.gradle.api.artifacts.dsl.DependencyHandler
 import org.gradle.api.logging.Logger
 import org.gradle.kotlin.dsl.DependencyHandlerScope
 import org.gradle.kotlin.dsl.closureOf
@@ -19,6 +20,7 @@ import org.gradle.kotlin.dsl.project
 import java.io.File
 
 private fun DependencyHandlerScope.implementation(dependency: Any) = dependencies.add("implementation", dependency)
+internal fun DependencyHandler.implementation(dependency: Any) = add("implementation", dependency)
 
 // Implementation + config block
 private fun DependencyHandlerScope.implementation(