[ci] add coverity support

- coverity scan is static analysis tool which is run by https://scan.coverity.com/
- coverity scan build is limited to 3 times one day https://scan.coverity.com/faq#frequency
- coverity scan is only to be run at branch coverity_scan (branch_pattern) due the reason above
- reports available [here](https://scan.coverity.com/projects/3121)