fix: properly free ssl session and ssl context

[rept1d]

Changes:

• Ensure that SSL_CTX is freed with SSL_CTX_free by using std::unique_ptr with custom deleter. Previously was leaking.
• Ensure that SSL is freed with SSL_free in ssl_client::cleanup(). Previously was leaking.
• Remove useless try-catch. If it failed to allocate, you have nothing to deallocate. The assignment doesn't even happen in this case, an exception is thrown when evaluating the right side.

Code change checklist

• I have ensured that all methods and functions are fully documented using doxygen style comments.
• My code follows the coding style guide.
• I tested that my change works before raising the PR.
• I have ensured that I did not break any existing API calls.
• I have not built my pull request using AI, a static analysis tool or similar without any human oversight.

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