Provide SSLSession in WebSocketClient

[marci4]

Description

Added SSLSession API with #890.
This was mainly added for the WebSocketServer. Make it also available in the client.

Related Issue

Fixes #1142

Motivation and Context

Bugfix

How Has This Been Tested?

Local test

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.