[staticcheck](https://github.com/bfenetworks/bfe/blob/develop/staticcheck.conf) had been used in `bfe`, but it doesn't exist in [ci job steps](https://github.com/bfenetworks/bfe/blob/develop/.github/workflows/ci.yml). Add step `staticcheck` on pull request and push develop, helps to improve quality of codes. marketplace [here](https://github.com/marketplace/actions/staticcheck), but it's under MIT license. Before using it, any license conflicts and CNCF policy limitations should take a care. - `bfe` under Apache License 2.0 and CNCF sandbox project