allow users to modify attributes of the tracking cookie

[mjkrivacek]

Description, Motivation and Context

When using the Nexus Websockets tracking cookie option it might be necessary to modify the cookie attributes. This is helpful when using Nexus WAMP over Websockets from a Web browser. Web browsers vary on the handling of cookies received.

What is the current behavior?

RESOLVES #295

What is the new behavior?

This change exposes two new websocket server settings that can be modified by the user. These settings control which SameSite mode that the nexus-wamp-cookie will be sent back with. Further, it allows the user to set the Secure attribute of the cookie to restrict the cookie to secure connections.

What kind of change does this PR introduce?

• 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 not work as expected)

Checklist:

• My code follows the code style of this project.
• I have added tests to cover my changes.
• Overall test coverage is not decreased.
• All new and existing tests passed.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.

(this is my first attempt at a PR of any kind. Please let me know what I might have missed)

[KSDaemon]

@mjkrivacek Great! Everything looks good: code, tests, pr description! Thank you for you contribution! 👍🏻