[550] Add support for client hints

[stsnel]

...I do have one question, though. Is the irods.session the right place for this? I don't use PRC enough to know of a better place, but just want to make sure we considered other designs (a new Model, a property of a Connection, etc.).

Right, I chose session.py initially, since it already has the server_version attribute, and it seemed logical to me to put attributes that show information about the server in the same place. But I'm also happy to move it elsewhere if that fits the design better.

[trel]

Note - this is information from the connected server only.... right?

[alanking]

Sold. Merging. Thanks!