[C++] pass custom arguments to tsi_create_ssl_*_handshaker_factory

[mira....@gmail.com]

We are using (runtime) interchangeable implementation of tls (read we update it during runtime)
This means we have to do some reference counting on loaded tls implementation, restart long-running connection to allow update and hack grpc sources to allow us to do this.
As upstream changes are always better option can anyone suggest a best way to do this ? (so I can do pull request to upstream and it would be acceptable by community)
I would like this as an option in channel properties (currently we have this hacked into ssl_config structure), but channel arguments are usually not passed directly into tsi but parsed and passed.

WDYT ?

[ncte...@google.com]

This feature would definitely need a gRFC, see this repo. I would suggest clarifying your ideas for the design a bit further, then posting them there to get feedback from gRPC team and from security team