adb: add `adb raw` to connect to an arbitrary service.

Add a command to connect to an arbitrary service, for debugging
purposes.

Test: `adb raw shell:ls`
Change-Id: I69d4d585e5ecfa7cb8c7a543a2a27df7033b26c7
diff --git a/adb/client/commandline.cpp b/adb/client/commandline.cpp
index 06fcf16..e07dba7 100644
--- a/adb/client/commandline.cpp
+++ b/adb/client/commandline.cpp
@@ -1795,6 +1795,11 @@
     }
     else if (!strcmp(argv[0], "track-devices")) {
         return adb_connect_command("host:track-devices");
+    } else if (!strcmp(argv[0], "raw")) {
+        if (argc != 2) {
+            return syntax_error("adb raw SERVICE");
+        }
+        return adb_connect_command(argv[1]);
     }