Split parcelable .aidl files to aidl-export

The one-line "parcelable X" files need to be imported by targets that do
not build against SDK (the SDK has prebuilt definitions), so prepare a
dedicated directory for them.
This avoids having users of the classes include the whole src/
directory, which could contain definitions for classes that are not part
of the public API, so should not be imported.

Also move back to frameworks/base/core some .aidl definitions that
were separated from their associated class.

Bug: 171540887
Test: m
Merged-In: I7432fe4c87cd3cab04dcb6185c9a4f3f84376549
Change-Id: I7432fe4c87cd3cab04dcb6185c9a4f3f84376549

core/java/android/net/UidRange.aidl

@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+package android.net;
+
+/**
+ * An inclusive range of UIDs.
+ *
+ * {@hide}
+ */
+parcelable UidRange;