Summary:
- Fix cmake build failure with gflags.
- Add CI tests for both gflags 2.1 and 2.2.
- Fix ctest config with gtest.
- Add CI to run test with ctest.

One benefit of ctest is it support timeout, it's set to 5min in our CI, so we will know which test is hang.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8324

Test Plan: CI pass

Reviewed By: ajkr

Differential Revision: D28762517

Pulled By: jay-zhuang

fbshipit-source-id: 09063c5af5f9f33abfcdeb48593acbd9826cd199