Add @bazel_tools//tools/jdk:javadoc

Fixes #6757

It adds a `@bazel_tools//tools/jdk:javadoc` alias similar to `@bazel_tools//tools/jdk:java`, which correctly maps to `javadoc.exe` on windows and `javadoc` elsewhere.

Closes #7898.

PiperOrigin-RevId: 251188709
diff --git a/src/main/tools/jdk.BUILD b/src/main/tools/jdk.BUILD
index 31fbb64..f632ea2 100644
--- a/src/main/tools/jdk.BUILD
+++ b/src/main/tools/jdk.BUILD
@@ -68,6 +68,16 @@
 
 filegroup(
     deprecation = DEPRECATION_MESSAGE,
+    name = "javadoc",
+    srcs = select({
+        ":windows": ["bin/javadoc.exe"],
+        "//conditions:default": ["bin/javadoc"],
+    }),
+    data = [":jdk"],
+)
+
+filegroup(
+    deprecation = DEPRECATION_MESSAGE,
     name = "xjc",
     srcs = ["bin/xjc"],
 )
diff --git a/tools/jdk/BUILD b/tools/jdk/BUILD
index a32404e..1c1e57f 100644
--- a/tools/jdk/BUILD
+++ b/tools/jdk/BUILD
@@ -128,6 +128,11 @@
     actual = "@local_jdk//:javac",
 )
 
+alias(
+    name = "javadoc",
+    actual = "@local_jdk//:javadoc",
+)
+
 # On Windows, executables end in ".exe", but the label we reach it through
 # must be platform-independent. Thus, we create a little filegroup that
 # contains the appropriate platform-dependent file.