Allow mainline IPsec(IKE) to statically include @PolicyDirection

@PolicyDirection was hidden API defined in IpSecManager and
mainline module IPsec(IKE) needs to depend on it.

To remove this hidden API dependency, this commit:
- Moves definition of @PolicyDirection to a separate class
- Creates sharing filegroup framework-ike-shared-srcs for mainline
  IKE and include PolicyDirection.java

Bug: 146360859
Test: build, flash, boot
Test: atest FrameworksIkeTests
Change-Id: Ic6d7c06d4b92e16a9a65430365c9acc73932147b

core/java/android/net/IpSecManager.java

@@ -17,7 +17,6 @@ package android.net;
 
 import static com.android.internal.util.Preconditions.checkNotNull;
 
-import android.annotation.IntDef;
 import android.annotation.NonNull;
 import android.annotation.RequiresFeature;
 import android.annotation.RequiresPermission;
@@ -26,6 +25,7 @@ import android.annotation.SystemService;
 import android.annotation.TestApi;
 import android.content.Context;
 import android.content.pm.PackageManager;
+import android.net.annotations.PolicyDirection;
 import android.os.Binder;
 import android.os.ParcelFileDescriptor;
 import android.os.RemoteException;
@@ -41,8 +41,6 @@ import dalvik.system.CloseGuard;
 
 import java.io.FileDescriptor;
 import java.io.IOException;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
 import java.net.DatagramSocket;
 import java.net.InetAddress;
 import java.net.Socket;
@@ -78,11 +76,6 @@ public final class IpSecManager {
      */
     public static final int DIRECTION_OUT = 1;
 
-    /** @hide */
-    @IntDef(value = {DIRECTION_IN, DIRECTION_OUT})
-    @Retention(RetentionPolicy.SOURCE)
-    public @interface PolicyDirection {}
-
     /**
      * The Security Parameter Index (SPI) 0 indicates an unknown or invalid index.
      *