Implement new tls channel biding types

Current support for tls channel binding extraction api (gnutls_session_channel_binding()) is very rudimentary (tls-unique only) and partial (does not work for TLSv1.3). This MR targets to add missing binding types to cover existing protocols (TLSv1.2 and TLSv1.3).

Closes #1041 (closed) Closes #1214 (closed)

Checklist

• Commits have Signed-off-by: with name/author being identical to the commit author
• Code modified for feature
• Test suite updated with functionality tests
• Test suite updated with negative tests
• Documentation updated / NEWS entry present (for non-trivial changes)
• CI timeout is 2h or higher (see Settings/CICD/General pipelines/Timeout)

Reviewer's checklist:

• Any issues marked for closing are addressed
• There is a test suite reasonably covering new functionality or modifications
• Function naming, parameters, return values, types, etc., are consistent and according to CONTRIBUTION.md
• This feature/change has adequate documentation added
• No obvious mistakes in the code