[skip ci] chore: Address deprecation warnings from gradle 8.5+ (#2637)

settings.gradle.kts

@@ -23,6 +23,20 @@ File(rootDir, "lib").eachDir {
     project(":lib-$libName").projectDir = File("lib/$libName")
 }
 
+// Fix deprecation warnings with Gradle 8.5+.
+// See https://docs.gradle.org/8.5/userguide/upgrading_version_8.html#deprecated_missing_project_directory
+listOf(
+    ":extensions" to "$rootDir/gradle", // Temporary workaround.
+    ":extensions:individual" to "$rootDir/src",
+    ":extensions:multisrc" to "$rootDir/generated-src",
+).forEach { (name, path) ->
+    val projectDir = file(path)
+    if (projectDir.exists()) {
+        include(name)
+        project(name).projectDir = projectDir
+    }
+}
+
 if (System.getenv("CI") == null || System.getenv("CI_MODULE_GEN") == "true") {
     // Local development (full project build)