Library module implementation check module may be unnecessary

https://github.com/googlesamples/android-custom-lint-rules/blob/4ff2f4d91773fb56c136b2b0b581cc4c0e39e72e/library/build.gradle#L20

If we add this implementation line, it will add a dependency of checks module after we publish to maven, but it is unnecessary because the aar will contain lint.jar.