Messaging: Remove duplicate code

* mmslib contains basically the same code as android.support.v7.mms.pdu
  does, so align them code-wise and remove the mmslib duplicates
* Since mmslib contains a few usages that are now not accessible
  anymore, make the classes or methods public where it complains

Change-Id: I10b8716c0e45079e4795fda4489dc1a9535026f3

src/com/android/messaging/mmslib/util/PduCacheEntry.java

@@ -1,6 +1,7 @@
 /*
  * Copyright (C) 2008 Esmertec AG.
  * Copyright (C) 2008 The Android Open Source Project
+ * Copyright (C) 2025 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +18,7 @@
 
 package com.android.messaging.mmslib.util;
 
-import com.android.messaging.mmslib.pdu.GenericPdu;
+import android.support.v7.mms.pdu.GenericPdu;
 
 public final class PduCacheEntry {
     private final GenericPdu mPdu;