Add support for client auth using TLS

[alesharik]

Closes #197
Fork of PR #267 , and it's rebase attempt, because seems like original PR is unmaintained

[lightistor]

@lhotari can we get assistance in getting this PR merged?

[lhotari]

Thanks for the contribution @alesharik. Would it be possible to add some tests to validate the added feature?
I'm not familiar to this code base and how it's tested.

[lhotari]

@freeznet @mattisonchao Please review this PR.

[alesharik]

Hi, @lhotari
I think yes. I'll look into that tomorrow

[lhotari]

Hi, @lhotari I think yes. I'll look into that tomorrow

@alesharik Thanks! There doesn't seem to be very many tests in the project currently. Improving on that in this area could require more effort than usual because of the lack of examples of how things are handled in pulsar-rs.

[alesharik]

@lhotari hi!
I added copy of roundtrip test which connects over TLS. Also added all necessary certs (in .github/certs), script to generate them and modified CI to run Pulsar in TLS+plain mode. It works on local machine when running Pulsar 3.1.3 with command provided in CI; but I am not sure if it will run in Github Actions