Implement com.google.devtools.build.lib.rules.apple.DottedVersion$Option toString()

This way, the string value shows up when running bazel config, instead of values such as `com.google.devtools.build.lib.rules.apple.DottedVersion$Option@1703e2`

Closes #12347.

PiperOrigin-RevId: 338992146

src/main/java/com/google/devtools/build/lib/rules/apple/DottedVersion.java

diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/DottedVersion.java b/src/main/java/com/google/devtools/build/lib/rules/apple/DottedVersion.java
index fd3d3e0..00f303c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/DottedVersion.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/DottedVersion.java
@@ -117,6 +117,11 @@
 
       return version.stringRepresentation.equals(((Option) o).version.stringRepresentation);
     }
+
+    @Override
+    public String toString() {
+      return version.toString();
+    }
   }
 
   public static DottedVersion maybeUnwrap(DottedVersion.Option option) {