TT-8317: Added KeyID to Session State Protobuf

[nerdydread]

Description

Added the keyID to the session state protobuf so that it can be available to gRPC plugins

Related Issue

https://tyktech.atlassian.net/browse/TT-8317

Motivation and Context

How This Has Been Tested

Wrote a gRPC plugin that printed the keyID to stdout.

Screenshots (if appropriate)

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Refactoring or add test (improvements in base code or adds test coverage to functionality)

Checklist

• [ ] I ensured that the documentation is up to date
• [ ] I explained why this PR updates go.mod in detail with reasoning why it's required
• [ ] I would like a code coverage CI quality gate exception and have explained why