Refactoring: Rewrite links in Metalava instead of carrying patches.

Another CL in this topic introduces the metalava feature flag
--replace-documentation <ancestor java packages> <regex> <replacement>
to perform regex replacements in the documentation of some elements.

This CL uses that feature to re-write links in libcore/ojluni/
documentation that previously carried patches.

Since .bp files don't appear to support String literals that are not
(un)escaped, \ and $ occurring in the regexp/replacement parameters
need to be escaped in the .bp file.

Bug: 129765390
Test: Manually checked that this CL topic does not affect the result of
      "make ds-docs offline-sdk-docs"

Change-Id: Idb7366530c4ab255c1348cf48881cf2bde31be1e

Android.bp

@@ -1155,7 +1155,22 @@ metalava_framework_docs_args = "--manifest $(location core/res/AndroidManifest.x
     "--hide RequiresPermission " +
     "--hide MissingPermission --hide BroadcastBehavior " +
     "--hide HiddenSuperclass --hide DeprecationMismatch --hide UnavailableSymbol " +
-    "--hide SdkConstant --hide HiddenTypeParameter --hide Todo --hide Typo"
+    "--hide SdkConstant --hide HiddenTypeParameter --hide Todo --hide Typo "
+
+// http://b/129765390 Rewrite links to "platform" or "technotes" folders
+// which are siblings (and thus outside of) {@docRoot}.
+//
+// We have to escape \ as \\ and $ as $$ here because they get resolved by
+// different layers of the build tooling. The arguments are wrapped in '' so
+// that the shell doesn't add yet another level of escaping.
+metalava_framework_docs_args += " --replace-documentation " +
+    // packages whose descendants to apply replacement to (all packages from
+    // libcore/ojluni/src/main/java that contribute to documentation).
+    "com.sun:java:javax:jdk.net:sun " +
+    // regex of the string to replace
+    "'(<a\\s+href\\s?=[\\*\\s]*\")(?:(?:\\{@docRoot\\}/\\.\\./)|(?:(?:\\.\\./)+))((?:platform|technotes).+)\">' " +
+    // replacement (with $1, $2 backreferences to the regex groups)
+    "'$$1https://docs.oracle.com/javase/8/docs/$$2\">' "
 
 stubs_defaults {
     name: "framework-doc-stubs-default",