check-flagged-apis: add new CLI to verify @FlaggedApi APIs

Add a new CLI to verify that the build artifacts contain the right set
of @FlaggedApi APIs, based on the value of the corresponding aconfig
flag.

This CLI will act as an end-to-end test of Soong and metalava.

This CL only adds the project scaffolding; later CLs will add the
implementation.

Bug: 334870672
Test: m check-flagged-apis && check-flagged-apis
Change-Id: Ib00653f2a549217da2b0058867c711f35efd5760
diff --git a/tools/check-flagged-apis/src/com/android/checkflaggedapis/Main.kt b/tools/check-flagged-apis/src/com/android/checkflaggedapis/Main.kt
new file mode 100644
index 0000000..dee4fdb
--- /dev/null
+++ b/tools/check-flagged-apis/src/com/android/checkflaggedapis/Main.kt
@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+@file:JvmName("Main")
+
+package com.android.checkflaggedapis
+
+fun main() = println("hello world")