Provide a default implementation of PlatformTestStorage openInternal apis.

These APIs will move to restricted scope in a subsequent CL.
and thus providing a default implementation ensures implementations
of PlatformTestStorage do not need to implement them.

PiperOrigin-RevId: 625063310

Author: brettchabot

runner/monitor/java/androidx/test/platform/io/PlatformTestStorage.java

@@ -101,7 +101,9 @@ public interface PlatformTestStorage {
    * @return an InputStream to the given test file.
    * @throws FileNotFoundException if pathname does not exist
    */
-  InputStream openInternalInputFile(String pathname) throws FileNotFoundException;
+  default InputStream openInternalInputFile(String pathname) throws FileNotFoundException {
+    return openInputFile(pathname);
+  }
 
   /**
    * Provides an OutputStream to an internal file used by the testing infrastructure.
@@ -110,7 +112,9 @@ public interface PlatformTestStorage {
    * @return an OutputStream to the given output file.
    * @throws FileNotFoundException if pathname does not exist
    */
-  OutputStream openInternalOutputFile(String pathname) throws FileNotFoundException;
+  default OutputStream openInternalOutputFile(String pathname) throws FileNotFoundException {
+    return openOutputFile(pathname);
+  }
 
   /**
    * Provides a Uri to a test file dependency.