Add SSL/TLS support

[Gor027]

Pre-review checklist

• [x] I have split my patch into logically separate commits.
• [x] All commit messages clearly explain what they change and why.
• [x] PR description sums up the changes and reasons why they should be introduced.
• [x] I have enabled appropriate tests in .github/workflows/build.yaml in gtest_filter.

This PR is dependent upon #69

This PR adds SSL/TLS support to the driver. Integration tests that are enabled in the C++ driver and are actually run during Jenkins builds, are also enabled for the cpp-rust-driver. One of the reasons that the SSL tests are disabled for cpp-driver is that during the setup scylla-ccm fails while trying to start a Scylla cluster. So, to make sure the SSL properly works, I have also run the integration tests on a Cassandra cluster.

[Gor027]

V2:

The SSL support is reimplemented, this time based on the openssl-sys crate which provides rust bindings for the original OpenSSL library. With this approach, it is possible to mirror the behavior of the SSL-related functions more closely. As before, the functionality was tested manually on ScyllaDB (some integration tests are enabled), and it was also tested on a Cassandra cluster.

[Gor027]

After logging support is merged into the master, the error checking/reporting functionality can be added to the SSL-related functions.