Add proto binary file type for downloading files from emulator (#79)

Author: rnakade

AndroidXCI/lib/src/main/kotlin/dev/androidx/ci/testRunner/TestRunnerService.kt

@@ -357,6 +357,7 @@ interface TestRunnerService {
             const val LOGCAT = "logcat"
             const val PNG = "png"
             const val TEXTPROTO = "textproto"
+            const val PROTOBINARY = "pb"
         }
     }