Add addService to pass in dump priority flags.

Bug: 342937835
Test: Service can be added with dump priority critical or high.

Signed-off-by: Henry Wang <wangzhenghong@google.com>
(cherry picked from https://android-review.googlesource.com/q/commit:acb3a5a9b214fbb7c54e94afe77bf4fb0f0793eb)
Change-Id: I59a3fa3662ae253b5d2ab89071603a6e6eb81349